u n i ve r s i t y o f co pe n h ag e n

Study of ordered hadron chains with the ATLAS detector

Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B; Abidi, Sarah; AbouZeid, O.S.;Abraham, NL; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B.S.; Adachi,Shin-ichi; Adamczyk, L.; Adelman, J P; Adye, T.; Affolder, A. A.; Dam, Mogens; Hansen, JørnDines; Hansen, Jørgen Beck; Xella, Stefania; Hansen, Peter Henrik; Petersen, TroelsChristian; Løvschall-Jensen, Ask Emil; xtf324, xtf324; Monk, James William; Pedersen, LarsEgholm; Wiglesworth, Graig; Galster, Gorm Aske Gram Krohn; Stark, Simon Holm; Besjes,Geert-Jan; Thiele, Fabian Alexander Jürgen; de Almeida Dias, Flavia; Bajic, MilenaPublished in:Physical Review D

DOI:10.1103/PhysRevD.96.092008

Publication date:2017

Document versionPublisher's PDF, also known as Version of record

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Citation for published version (APA):Aaboud, M., Aad, G., Abbott, B., Abdinov, O., Abeloos, B., Abidi, S., ... Bajic, M. (2017). Study of ordered hadronchains with the ATLAS detector. Physical Review D, 96(9), [092008].https://doi.org/10.1103/PhysRevD.96.092008

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Study of ordered hadron chains with the ATLAS detector

M. Aaboud et al.*

(ATLAS Collaboration)(Received 22 September 2017; published 29 November 2017)

The analysis of the momentum difference between charged hadrons in high-energy proton-protoncollisions is performed in order to study coherent particle production. The observed correlation patternagrees with a model of a helical QCD string fragmenting into a chain of ground-state hadrons. A thresholdmomentum difference in the production of adjacent pairs of charged hadrons is observed, in agreementwith model predictions. The presence of low-mass hadron chains also explains the emergence ofcharge-combination-dependent two-particle correlations commonly attributed to Bose-Einstein interfer-ence. The data sample consists of 190 μb−1 of minimum-bias events collected with proton-protoncollisions at a center-of-mass energy

ffiffiffis

p ¼ 7 TeV in the early low-luminosity data taking with the ATLASdetector at the LHC.

DOI: 10.1103/PhysRevD.96.092008

I. INTRODUCTION

Studies of correlated hadron production are an importantsource of information about the early stages of hadronformation, not yet understood from the theory of stronginteractions. Although experimental high-energy physicsemploys several phenomenologicalmodels of hadronizationthat describe the formation of jets with remarkable accuracy,correlation phenomena are more elusive. In particular, theobserved excess of nearby equally charged hadrons—commonly attributed to Bose-Einstein interference—hasnever been satisfactorily reproduced by Monte Carlo(MC) models, despite several decades of intensive mea-surements. Furthermore, dedicated studies of these corre-lations in WW production at LEP2 did not confirm theexpected presence of correlations between hadrons origi-nating from different color-singlet sources [1].Recently, it was pointed out that correlations between like-

sign hadrons arise in the causality-respecting model ofquantized fragmentation of a three-dimensional QCD string[2], as a consequence of coherent hadron emission [3]. Thetopology of the string and the causal constraint implementedin this model define the mass spectrum and the correlationpattern of emitted hadrons. This analysis investigates observ-ables sensitive to predictions of the quantized string model.The experimental technique is focused on the extraction of asignal from correlated hadron pairs and triplets.The paper is organized as follows. Section II contains a

brief overview of phenomenological aspects of the quan-tized three-dimensional QCD string. Section III recounts the

observable features of the model and outlines the strategy ofthe analysis. Section IV describes the ATLAS detector. Thedata selection and MC event generators are described inSection V. Section VI shows the measured data. Correctionof the data to the particle level is described in Sec. VII.Section VIII contains the results and the studies of system-atic uncertainties. Section IX is devoted to the interpretationof results, and Sec. X contains concluding remarks.

II. PHENOMENOLOGY OF QCD STRINGFRAGMENTATION

The Lund string fragmentation model [4], which isimplemented in the PYTHIA event generator [5], uses aone-dimensional string to model the QCD confinement.The string is broken randomly by the production of a newquark-antiquark pair (or a pair of diquarks if baryons are tobe produced). Hadron four-momenta are determined by therelative position and timing of adjacent breakup vertices.Hadrons sharing a common breakup vertex are calledadjacent hadrons. The model imposes a spacelike distancebetween the vertices in order to produce hadrons with apositive (physical) mass. Despite the absence of a causalconnection between vertices, the adjacent string breakupscannot be treated as random because they define the mass ofthe created hadron. The mass spectrum is enforced in themodel by adding the mass constraint to the kinematics of thestring decay, using hadron masses and widths as externalparameters. The model relies on the concept of quantumtunneling to generate the intrinsic transverse momenta ofhadrons; the partons created in the string breakup areassigned a transverse momentum with a constant azimuthaldistribution andwith amagnitude drawn randomly accordingto a Gaussian distribution with a tunablewidth. Local chargeand momentum conservation hold in the breakup vertex, butaccording to the model, there are no correlations betweennonadjacent hadrons in the string’s transverse plane.

*Full author list given at the end of the article.

Published by the American Physical Society under the terms ofthe Creative Commons Attribution 4.0 International license.Further distribution of this work must maintain attribution tothe author(s) and the published article’s title, journal citation,and DOI.

PHYSICAL REVIEW D 96, 092008 (2017)

2470-0010=2017=96(9)=092008(31) 092008-1 © 2017 CERN, for the ATLAS Collaboration

The one-dimensional string serves as an approximationfor a more complex QCD field shape, which may be similarto a thin vortex of a type-II superconductor. The possibilityof understanding the shape of a QCD string in threedimensions was first studied in Ref. [3] with the goal ofinvestigating effects stabilizing the end of the partonshower cascade. On the basis of angular properties ofgluon emission under helicity conservation, the authors ofRef. [3] concluded that collinear gluon emissions areabsent. On the basis of optimal packing of soft noncollineargluon emissions, it was deduced that the shape of the QCDstring should be helixlike.The fragmentation in the transverse plane changes

substantially when a one-dimensional string is replacedby a three-dimensional string and quantum tunneling isreplaced by gluon splitting into a quark-antiquark pair withnegligiblemomentum in the rest frameof the string stretchedbetween the color-connected partons. Fragmentation of sucha string generates intrinsic transverse momentum thatdepends on the folding of the string and implies azimuthalcorrelations between hadrons. Azimuthal correlations com-patible with the helical shape of the QCD string have beenobserved by ATLAS [6].A fragmentation model working with a three-

dimensional string enables cross-talk between breakupvertices to be introduced. When the causal constraint isimposed on the fragmentation of a helical QCD stringdescribed by radius R and phase Φ (Fig. 1), the massspectrum of light mesons is reproduced by a string breakingin regular ΔΦ intervals. A fit of the mass spectrum ofpseudoscalar mesons indicates a rather narrow radius of thehelical string (κR ¼ 68� 2 MeV, where κ ∼ 1 GeV=fm isthe string tension) and a quantized phase difference ΔΦ ¼2.82� 0.06 [2].The effective quantization of the string fragmentation

predicts correlations between pairs of hadrons producedalong the string, as a function of their rank difference r.1

Correlations can be studied with help of the momentumdifference Q,

Qij ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi−ðpi − pjÞ2

q; ð1Þ

wherepi,pj stand for the four-momenta of particles formingthe pair. The numerical values of the predicted momentumdifference separating pairs of ground-state pions2 with rankdifferences up to 5 are given in Table I. Predictions arecalculated in the limit of a locally homogeneous string fieldwith regular helix winding, which implies a vanishinglongitudinal momentum difference between pions in thechain. Adjacent pions are produced with an intrinsic trans-verse momentum difference of ∼266 MeV, which can beseen as a quantum threshold for the production of adjacenthadrons. In a chain of adjacent charged pions, local chargeconservation allows for the production of pairs of pions withequal charge for even rank differences (r ¼ 2; 4; ...) andopposite charge for odd rank differences (r ¼ 1; 3; ...) only.The low-Q region (Q < 100 MeV) is populated by pairswith r ¼ 2.Within the model, a chain of n adjacent ground-state

pions has the smallest possible mass for a chain of nadjacent hadrons. It can be calculated using the relation

mn ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffin2m2

π þXi≠j

Q2ij

s; ð2Þ

where mπ ¼ mn¼1 is the pion mass and Qij stands for themomentum difference of pairs of hadrons forming thechain. Further information about the calculation of modelpredictions is provided in Appendix A.

III. OBSERVABLE QUANTUM PROPERTIESOF STRING FRAGMENTATION

The analysis uses the two-particle correlations measuredfor like-sign and opposite-sign hadron pairs to study themomentum difference between adjacent hadrons. Thepossible connection between the enhanced production ofequally charged pions at low Q and the production of

FIG. 1. Left: Parametrization of the helical shape of the QCD string. Middle: In quantized string fragmentation, the breakup points areseparated by the quantized helix phase difference n ΔΦ, n ¼ 1 for the ground-state pion. Right: The shape of the QCD string is reflectedin the momentum distribution of emitted hadrons. The intrinsic transverse momentum of hadrons pTðnÞ is quantized (see the Appendix).The azimuthal angle between intrinsic transverse momenta of adjacent ground-state pions is equal to ΔΦ.

1The rank refers to the ordering of hadrons along the string;adjacent pairs have rank difference 1.

2The term ground-state pion denotes the lightest hadron stateformed by a string piece with a helix phase difference ΔΦ, with acausal relation imposed on the end point breakup vertices.

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chains of adjacent ground-state pions is investigated. Forthat purpose, correlations are measured for a selection ofexclusive hadron triplets designed to isolate the sourceof correlations (see Sec. III A) and compared in detail to theinclusively measured two-particle correlations [7,8]. Thecorrelation function is defined in a way that facilitatesthe measurement of adjacent hadron pairs (see Sec. III B).

A. Analysis strategy: Chain selection

The shortest chain of hadrons from which the propertiesof a helix can be inferred experimentally is a chain of threecharged hadrons (þ −þ;−þ −), labeled 3h. For the chainselection, it is sufficient to consider only qualitativepredictions of the model. It is experimentally impossibleto reconstruct the history of string fragmentation from themomenta of final-state particles only, since the rank differ-ence of any given pair of hadrons is unknown a priori.However, according to the model, a chain of ground-statepions will have the lowest possible mass as compared to achain of arbitrary hadrons, and the smallest momentumdifference within the chain of charged ground-state pionsshould be carried by the pair of like-sign pions. Therefore,the chain selection procedure is defined, event by event, inthe following way:(1) Each measured particle is paired with the like-sign

particle thatminimizes the pairmomentumdifferenceQ calculated from the measured three-momenta. Thepion mass is assigned to all particles.3

(2) Each pair is supplemented with an oppositelycharged particle chosen to minimize the triplet mass.The resulting three-particle system, (þ −þ) or(−þ −), is labeled as chain in the following, asthe charge-conservation constraint is applied todefine the relative ordering of particles. The chainselection is further refined in order to avoid double-counting of particle pairs. The following criteria—rooted in the underlying physics picture of stringfragmentation, illustrated in Fig. 2—are applied inan iterative way, preserving the configurations withlowest mass found so far.

(3) The association of particles is verified, in the orderof increasing pair momentum difference. If a particleis associated with more than two different like-signpartners, the two pairs with smallest momentumdifference are retained, and the remaining associa-tions are discarded. A new search for a closest like-sign partner is performed using the still-availableparticles. Since the algorithm allows a pair of like-sign particles to be associated with two differentchains, each protochain is assigned a weight of wi ¼0.5 or wi ¼ 1 accordingly, to prevent the double-counting of identical chains.

(4) After completion of chains with opposite-sign ha-drons, the association rate of all opposite-sign pairsin the chain selection is verified, in the order ofincreasing chain mass. According to the stringfragmentation picture, a pair of adjacent hadronscan be shared by at most two adjacent triplet chains(Fig. 2). In the case where a pair of opposite-signhadrons belongs to three or more selected chains, thetwo chains with lowest mass are retained, and a newsearch for an opposite-sign partner is performed forthe other chains. If that search fails, the weight of thecorresponding chain is set to zero. Zero weight isalso assigned to incomplete chains if there are notenough particles in the event to construct triplets.

At the end of the procedure, the chain selection containsnch chains in an event with nch charged particles, and someof these chains are effectively eliminated, having zeroweight. The requirement for the like-sign pair to carry thesmallest momentum difference within the chain is notimposed in any way; only ∼1=3 of selected chains containssuch a configuration. Although the chain selection buildson generic properties of chains of ground-state hadrons byminimizing both the momentum difference for like-signpairs and the mass of triplets, the numerical predictions ofthe helical string model are not used in the chain selection.For the sake of simplicity, the analysis is restricted to thestudy of triplet chains only.

B. Analysis strategy: Definition of thecorrelation function

In the picture of the string fragmentation, the number ofpairs of adjacent hadrons or pairs of hadrons with a fixedrank difference is proportional to the number of chargedparticles in the sample, while the total number of particlepairs grows quadratically with particle multiplicity. Thechoice of the correlation function is therefore driven by theneed to separate the signal from adjacent hadron pairs andthe large combinatorial background.In the fragmentation of a QCD string, the creation of

adjacent like-sign pairs is forbidden by local chargeconservation. For higher rank differences, the like-signand unlike-sign pairs should be produced in equal amountsdue to the random production of neutral hadrons in the

TABLE I. The expected momentum difference between ha-drons formed by fragmentation of a homogeneous string into achain of ground-state pions, in the quantized helix string model(see the Appendix). The 3% uncertainty is derived from theprecision of the fit of the mass spectrum of light pseudoscalarmesons (π; η; η0) [2].

Pair rank difference r 1 2 3 4 5

Q expected (MeV) 266�8 91�3 236�7 171�5 178�5

3Throughout this paper, the pion mass is assigned to allcharged particles in the data and in the MC simulation to reflectthe absence of particle identification in the data.

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chain. It follows that the subtraction of like-sign pairsfrom the opposite-sign pairs is a suitable technique forisolating the signal from adjacent hadron pairs. Theinclusive correlations are therefore assessed by the corre-lation function

ΔðQÞ ¼ 1

Nch½NðQÞOS − NðQÞLS�; ð3Þ

where Nch stands for the number of charged particles in thesample and NðQÞOSðNðQÞLSÞ denotes the inclusive spec-trum of opposite-sign (like-sign) pairs in the sample:

NðQÞOS ¼XNev

k¼1

Xnkchi;j¼1;i≠j

δðqi þ qjÞδðQ −QijÞ;

NðQÞLS ¼XNev

k¼1

Xnkchi;j¼1;i≠j

δðqi − qjÞδðQ −QijÞ: ð4Þ

The δðxÞ ¼ 1 − sign2ðxÞ corresponds to the Kroneckerdelta with a continuous argument, which is 1 for x ¼ 0

and zero otherwise.Nev stands for the number of events, nkchis the number of charged particles in event k, and qi is thecharge of particle i. The integral of the ΔðQÞ distributiondepends on the distribution of the total event charge only,with an upper limit of 0.5 for a sample of events withan equal number of negatively and positively chargedparticles. Experimentally, the restricted reconstructionacceptance creates a charge imbalance, which implies alarger loss of opposite-sign pairs compared to that of like-sign pairs and hence diminishes the integral of ΔðQÞdistribution.The properties of the correlation function were verified

on MC samples where no correlations were introducedbeyond local charge and momentum conservation in thestring breakup. The subtraction of inclusive pair distribu-tions provides the same result as the extraction of trueadjacent pairs, up to the uncertainty in the particle orderinggenerated by the presence of resonances decaying into threeand more charged hadrons [see Fig. 8(a) for illustration].This implies that the definition of the correlation function to

a large extent compensates for not knowing the exacthadron ordering in the string fragmentation. Traditionally,correlation studies employ a ratio of Q distributions ratherthan a difference, assuming incoherent or collective effects.Such an approach, however, does not eliminate the com-binatorial background from the measurement, and thereforeit is far less suitable for the measurement of the hadroniza-tion effects. A comparison of the two approaches isdiscussed in Sec. IX B.In direct correspondence to Eq. (3), the correlations

carried by exclusive three-hadron chains can be expressedas a sum over contributions from all chains with nonzeroweight,

Δ3hðQÞ ¼ 1

Nch

XNev

k¼1

Xnkchi¼1

wi

�1

2δðQ −Qi

01Þ þ1

2δðQ −Qi

12Þ

− δðQ −Qi02Þ

�; ð5Þ

where each chain contributes with three entries: two foropposite-sign pairs at Q01, Q12 and one for the like-signpair at Q02 (the indices reflect charge ordering of particlesin the chain). The wi stand for the weight factor of the ithchain in the event.The scaling of the opposite-sign pair contribution by 1=2

in Eq. (5) is required for proper subtraction of randomcombinations; physicswise, it corresponds to a hypothesisof an uninterrupted chain of charged hadrons where neigh-boring triplets share an opposite-sign pair, Fig. 2(a). Theestimate for disconnected triplets [Fig. 2(b)], where theopposite-sign pairs are not shared and should be countedwithweight 1, can be obtained from themeasurement ofΔ3h(after subtraction of random combinations), by rescaling theopposite-sign pair contribution—the positive part of theΔ3hðQÞ spectrum—by a factor of 2.

C. Analysis strategy: Three-body decay

Quantized fragmentation of the helical string into a chainof charged pions is expected to produce a distinct three-body decay pattern. The chain members are separated by amomentum difference that depends on their rank difference

FIG. 2. A schematic view of a string fragmentation into (a) a long uninterrupted chain and (b) disconnected three-hadron chains. Thecircles represent charged hadrons, and the black lines indicate the ordering according to the string fragmentation history (they connectadjacent hadron pairs). Dashed triangles indicate the triplet chains. In the long uninterrupted chain (a), neighboring triplets share acommon opposite-sign pair.

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(Table I). For a triplet chain, such a signal can be studiedwith the help of a Dalitz plot. In analogy with studiesof η decay [9,10], the Dalitz plot coordinates (X; Y) aredefined as

X ¼ffiffiffi3

p T0 − T2

Σ2i¼0Ti

; Y ¼ 3T1

Σ2i¼0Ti

− 1; ð6Þ

where Ti denotes the kinetic energy EiðmπÞ −mπ ofcharge-ordered particles in the rest frame of the chain(particles 0 and 2 form the like-sign pair). The method ofcalculation of predictions of the helix-string model can befound in the Appendix [Eq. (A3)].

IV. ATLAS DETECTOR

The ATLAS detector [11] covers almost the entire solidangle around the collision point with layers of trackingdetectors, calorimeters, and muon chambers. For themeasurements presented in this paper, the trigger systemand the tracking devices are of particular importance. Thefollowing description corresponds to the detector configu-ration in the first LHC data-taking period (Run 1).The ATLAS inner detector has full coverage in ϕ and

covers the pseudorapidity range jηj < 2.5.4 It consists of asilicon pixel detector, a silicon strip detector (SCT), and atransition radiation tracker (TRT). These detectors areimmersed in a 2 T axial magnetic field. The pixel, SCT,and TRT detectors have typical r–ϕ position resolutions of10, 17, and 130 μm, respectively, and the pixel and SCTdetectors have r–z position resolutions of 115 and 580 μm,respectively. A track traversing the full radial extent wouldtypically have 3 silicon pixel hits, 8 or more silicon striphits, and more than 30 TRT hits.The ATLAS detector has a three-level trigger system:

level 1 (L1), level 2 (L2), and the event filter (EF). For thismeasurement, the L1 trigger relies on the beam pickuptiming devices (BPTX) and the minimum-bias triggerscintillators (MBTS). The BPTX are composed of electro-static beam pickups attached to the beam pipe at a distancez ¼ �175 m from the center of the ATLAS detector. TheMBTS are mounted at each end of the inner detector infront of the end cap calorimeter at z ¼ �3.56 m and aresegmented into eight sectors in azimuth and two rings inpseudorapidity (2.09 < jηj < 2.82 and 2.82 < jηj < 3.84).Datawere taken for this analysis using the single-armMBTStrigger, formed from BPTX and MBTS L1 trigger signals.The MBTS trigger was configured to require one hit above

threshold from either side of the detector. TheMBTS triggerefficiency was studied with a separate prescaled L1 BPTXtrigger, filtered to obtain inelastic interactions by innerdetector requirements at L2 and the EF [12].

V. DATA SELECTION AND MC EVENTGENERATORS

Event and track selection are identical to those used inRefs. [7,12]. The data sample consists of 190 μb−1 ofminimum-bias events collected with proton-proton colli-sions at a center-of-mass energy

ffiffiffis

p ¼ 7 TeV in the early2010 ATLAS data taking with negligible contribution fromadditional pp collisions in the same bunch crossing.Events must:

(i) pass a single arm MBTS trigger,(ii) have a primary vertex reconstructed with at least two

associated tracks each with transverse momentum(pT) above 100 MeV,

(iii) not have a second primary vertex reconstructed withmore than three tracks,

(iv) have at least two good tracks, as defined below.A reconstructed track passes the selection if it has:

(i) pT > 100 MeV and lies in the pseudorapidityrange jηj < 2.5;

(ii) absolute values of transverse and longitudinal im-pact parameters below 1.5 mm, with respect to theevent primary vertex;

(iii) a hit in the first pixel layer when expected and atleast one pixel hit in total;

(iv) at least two (for pT>100MeV), four (for pT >200 MeV), or six (for pT> 300MeV) SCT hits;

(v) a fit probability above 0.01 for pT > 10 GeV.The sample contains ∼10 million events and over

200 million reconstructed tracks. The detector effects areevaluated using a PYTHIA6.421 [13] event sample withparameter values from the MC09 tune [14], fully simulated[15] and reconstructed using the standard ATLASreconstruction chain [16]. According to MC estimates,the selected set of reconstructed charged particles consistsof 86% pions, 9.5% kaons, 4% baryons, and 0.5% leptons,while the fraction of nonprimary particles is 2.3%. Primaryparticles are defined as all particles with a lifetime longerthan 0.3 × 10−10 s originating from the primary interactionor from subsequent decay of particles with a shorter lifetime.Correlation effects that are studied in the present analysis

are absent in hadronizationmodels, and therefore the analysisdoes not rely on MC predictions. For illustration, the dataare compared with a representative set of hadronizationmodels including PYTHIA8 (4C tune [17]), HERWIG++

[18,19] and EPOS [20].

VI. CORRELATION FUNCTIONS ATDETECTOR LEVEL

The inclusive distribution ΔðQÞ—as obtained fromreconstructed data—is shown in Fig. 3. It shows an

4ATLAS uses a right-handed coordinate system with its originat the nominal interaction point (IP) in the center of the detectorand the z axis along the beam pipe. The x axis points fromthe IP to the center of the LHC ring, and the y axis points upward.Cylindrical coordinates ðr;ϕÞ are used in the transverseplane, ϕ being the azimuthal angle around the beam pipe. Thepseudorapidity is defined in terms of the polar angle θ asη ¼ −ln tanðθ=2Þ.

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enhanced production of like-sign hadron pairs at low Q,visible as a negative value. The effect is quantified by thecorrelation strength (CS) defined as the absolute value ofthe integral of the negative part of the ΔðQÞ distribution

CS ¼ −ZΔ<0

ΔðQÞdQ: ð7Þ

The correlation function measured for three-hadronchains, Δ3hðQÞ, exhibits a shape similar to ΔðQÞ at lowQ (Fig. 3). However, the shape of the Δ3hðQÞ also dependson the upper mass limit, mcut

3h , imposed on the chainselection. The chain correlation strength (CCS) is defined as

CCSðmcut3h Þ¼−

ZΔ3h<0

Δ3hðQÞdQ; form3h <mcut3h : ð8Þ

A comparison of the two distributions suggests that theselection of triplet hadron chains with minimized mass maycontain the source of two-particle correlations observed inthe inclusive sample, but this information is indicative onlyat this stage due to the absence of unfolding of detectoreffects that affect the triplet selection more than theinclusive two-particle spectra. The average reconstructionefficiency for a pair of charged particles is ∼50%, and for atriplet of charged particles, it drops to ∼35%.

VII. CORRECTION TO PARTICLE LEVEL

The data are corrected for detector effects within theacceptance requirements (pT > 100 MeV, jηj < 2.5) fol-lowing the correction procedure established in Ref. [12].The track reconstruction inefficiency, the presence ofnonprimary tracks, and the migration of tracks acrossthe acceptance boundaries are corrected for by applying

track-based weights. The vertex and trigger efficiency iscorrected for with an event-based weight. The dominantcomponent of the uncertainty of the track weighting factorscomes from the dependence on the generated MC sample.Anticipating a strong contribution to the measurement fromthe low-pT region, the fully simulated PYTHIA6 sample issplit into nondiffractive and diffractive components. Theformer is used to calculate track-based weights, and thelatter is used to evaluate the uncertainty of the correction inthe low-pT region. The observed difference for the inclu-sive Q spectra [Eq. (4)] is ∼10%, without a significant Qdependence. The uncertainty of the track weighting factorsdue to the imperfect detector description is evaluated usingMC samples simulated and reconstructed with a 10%increase of material in the inner detector, which corre-sponds to the uncertainty of the detector description(Ref. [12]). The observed change of the inclusive Q doesnot exceed 2%. Both effects are combined and translatedinto an effective single-track weight uncertainty of 5%.The study of hadron pairs is sensitive to detector effects

related to the proximity of reconstructed tracks that are notexplicitly included in the track-based weights; the reducedreconstruction efficiency for pairs of tracks with a very lowopening angle and the correlated nonprimary particleproduction are taken into account via additional correctionfactors and additional systematic uncertainty. Both areparametrized in MC samples as a function of the openingangle between particles, and the parametrization is con-volved with the opening-angle distribution obtained fromthe data. The subtraction of the like-sign hadron pairspectrum from the opposite-sign pair spectrum implies alarge cancellation of these effects and cancellation ofsystematic effects in general. This renders the experimentaltechnique very robust. The uncertainty of track-basedweights is effectively removed from the integral of theΔðQÞ distribution thanks to the appropriate choice of thenormalization. The residual bias of the pair-correctionprocedure is evaluated in MC samples and added to the pairreconstruction systematic uncertainty. Figure 4(a) shows theQ dependence of the ΔðQÞ uncertainty related to thecombined pair reconstruction uncertainty and its compo-nents. The uncertainty is larger than (or comparable to) thecorrection observed in the MC simulation. The correctedinclusive two-particle Q spectra for like-sign and opposite-sign pairs used in this analysis, NðQÞLS and NðQÞOS, werepublished earlier [7] and can be obtained from Ref. [8].The correction of triplet chains needs to take into account

the impact of the track reconstruction inefficiency on thechain selection algorithm described in Sec. III A. Thecorrection for this effect is handled by the HBOM correc-tion technique [21]. In the HBOM method, the recon-structed tracks are randomly removed from the sampleaccording to the detector reconstruction efficiency, which isparametrized in terms of charged-particle pT and pseudor-apidity. Hence, the HBOM iteration corresponds to the

Q [GeV]

-110 1

(Q)

0

0.001

0.002

0.003

0.004-1bμ190 = 7 TeV sUncorrected data,

(inclusive)

< 0.54 GeV3h

, m3h

< 0.59 GeV3h

, m3h

< 0.64 GeV3h

, m3h

ATLAS

FIG. 3. Comparison of Δ3h (constructed from pairs belongingto the exclusive three-particle chain selection) with Δ (inclusivetwo-particle distribution), as a function of the upper limit on themass of selected three-hadron chains for uncorrected data.

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folding of the data with detector effects. The chain selectionis repeated using remaining tracks, for several HBOMfolding iterations, and the results are used to establish thefunctional dependency of the measured quantity on detec-tor effects. The parametrization of this dependency is thenextrapolated to the detector-effect free (zeroth foldingiteration) result. The statistical correlations betweenHBOM folding iterations are suppressed by resamplingthe probability to retain a given track in each foldingiteration independently.The systematic uncertainty of the HBOM method is

extracted directly from the data by performing an additionalHBOM unfolding to the detector level, where the detector-level data are taken as the reference and compared to theHBOM unfolding based on remaining folding iterations.The relative correlation strength CCS/CS is unfolded

using the HBOM technique as shown in Fig. 4(b) for achain mass-limit value of 0.59 GeV. The raw data and threeHBOM folding iterations are fitted using a second-orderpolynomial. Within the CS and CCS integral ranges,statistical uncertainties of CS and CCS are highly corre-lated, and therefore the statistical uncertainties of inputpoints are calculated assuming maximal overlap betweensamples. The extrapolation of the fitted function to thezeroth folding iteration yields the unfolded result and thestatistical error estimate. The systematic uncertainty is splitinto two components indicated on the plot: the combinedpair reconstruction uncertainty that is considered fullycorrelated between HBOM iterations and the uncertaintyof the folding factors, equal to the uncertainty of track-based weights discussed above.The analysis employs two different techniques in order

to correct the shape of Δ3h. The generic correction consistsin the evaluation of the fraction and of the shape of chainsaffected by track recombination. A chain which does notlose any track in a given HBOM folding iteration is labeled

as a “surviving” chain. The chain survival probability forthe ith HBOM iteration (i > 1) is calculated as the numberof chains surviving from the (i-1)th iteration divided by thenumber of chains selected in the ith iteration. Figure 5(a)shows, for a fixed chain mass limit, the chain survivalprobability as measured for three consecutive HBOMfolding iterations. The chain recombination probability iscomplementary to the chain survival probability. It servesas an input for the unfolding of the recombination prob-ability at the detector level (∼34% for a chain mass limit of0.59 GeV). The distribution of Δ3hðQÞ for the recombinedchains is obtained as a difference between the Δ3hðQÞdistribution obtained in a given folding iteration and theΔ3hðQÞ distribution of chains surviving from the previousiteration. The shape of Δ3hðQÞ for the recombined chains,together with the normalization obtained from the unfoldedrecombination rate, is used to produce an estimate of thecontribution of recombined chains to the detector-levelmeasurement. After subtraction of the recombined chains,the raw data are unfolded using track-based weight factors,in analogy with the unfolding of inclusive pair spectra.The second technique is designed to unfold the para-

metrized shape ofΔ3hðQÞ, which is well approximated by asum of two Gaussian functions describing the residualdifference between the opposite-sign and like-sign paircontent,

Δ3hðQÞ ¼ fLSðQ;QLS; σLSÞ þ fOSðQ;QOS; σOSÞ

¼ nLS exp

�−ðQ −QLSÞ2

2σ2LS

�

þ nOS exp�−ðQ −QOSÞ2

2σ2OS

�; ð9Þ

where nLS < 0 (nOS > 0) are scale factors, QLSðQOSÞindicate the position of Gaussian peaks, and σLS (σOS)

Q [GeV]

-110 1

)/N

(Q)

(

-0.02

-0.01

0

0.01

0.02

)/N(Q)(Scaled systematic uncertainty

combined

small opening angle

non-primary tracks

correction procedure

ATLAS

Data, −1bμ = 7 TeV, 190s

(a)

HBOM folding iteration

0 1 2 3 4

CC

S /

CS

0.4

0.6

0.8

1

ATLAS

/ndf = 0.8 / 12

< 0.59 GeV3hm

-1bμ = 7 TeV, 190 sData,

relative correlation strength

HBOM unfolding fit

unfolded relative corr. strength

5%±folding factor (per track)

(b)

FIG. 4. (a) Components of the systematic uncertainty of ΔðQÞ related to the reconstruction of pairs of tracks normalized to thecombined inclusive spectrum NðQÞ ¼ NðQÞOS þ NðQÞLS. (b) HBOM fit (red curve), which provides the corrected relative correlationstrength (red square marker). The systematic uncertainty is split into pair reconstruction uncertainty (error bar superimposed over theraw data point) and the variation of track folding factors (green lines).

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correspond to the width of peaks, for like-sign (opposite-sign) pairs.The shape is fitted for four folding iterations

(including the raw data), and the fit parameters andcorrelations between them are unfolded using theHBOM technique. Figure 5(b) shows the fits of theΔ3hðQÞ distribution for the m3h < 0.59 GeV, in the fit

range Q ∈ ð0.03; 0.33Þ GeV. The bin errors of fitteddistributions are statistical only.Figure 6 shows the HBOM unfolding extrapolation of

the fit parameters: the position and the width of the negative[like-sign pair (LS)] peak and the position and the width ofthe positive [opposite-sign pair (OS)] peak. The stability ofthe unfolding fit is evaluated using a fit with a polynomial

HBOM folding iteration

1 2 3 4

Sur

viva

l or

reco

mbi

natio

n pr

obab

ility

0

0.2

0.4

0.6

0.8

1

recombination probability

survival probability

cumulated recombination prob.

-1bμ = 7 TeV, 190s Data,

< 0.59 GeV3h m

ATLAS

(a)

Q [GeV]

0.1 0.2 0.3

(Q)

3h

-0.4

-0.2

0

0.2

0.4

-310×

HBOM folding iterationsfolding iteration 1 (raw data)

folding iteration 2

folding iteration 3

folding iteration 4

-1bμ = 7 TeV, 190s Data,

ATLAS

(b)

FIG. 5. Demonstration of the HBOM unfolding procedure. (a) Unfolding fit of the chain recombination probability, used to correct therecombination effects in the detector-level chain selection. The cumulated recombination probability corresponds to the fraction of“nonoriginal” chains—those not existing at the particle level—in each HBOM iteration. (b) Δ3h per HBOM iteration, for a chain masslimit of 0.59 GeV, fitted with a double-Gaussian parametrization. Both plots show statistical errors only.

/ ndf 2 0.5 / 2

p0 0.00044! 0.08946

p1 0.000267! -0.001844

HBOM folding iteration

0 1 2 3 4

[G

eV]

LSQ

0.08

0.085

0.09

/ ndf 2 = 0.5 / 2

ATLAS

< 0.59 GeV3hm

-1bμ = 7 TeV, 190 sData,

/ ndf 2 2.6 / 2

p0 0.0005! 0.2558

p1 0.00035! -0.00398

HBOM folding iteration

0 1 2 3 4

[G

eV]

OS

Q

0.24

0.25

/ ndf 2 = 2.6 / 2

ATLAS

-1bμ = 7 TeV, 190 sData,

< 0.59 GeV3hm

/ ndf 2 = 1.365 / 2

ATLAS

HBOM folding iteration

0 1 2 3 4

[G

eV]

LS

0.04

0.042

0.044

/ ndf 2 = 1.4 / 2

ATLAS

< 0.59 GeV3hm

-1bμ = 7 TeV, 190 sData,

/ ndf 2 2.282 / 2

p0 0.00058! 0.04394

p1 0.000375! 0.000725

HBOM folding iteration

0 1 2 3 4

[G

eV]

OS

0.042

0.044

0.046

0.048

/ ndf 2 = 2.3 / 2

ATLAS

< 0.59 GeV3hm

-1bμ = 7 TeV, 190 sData,

FIG. 6. The unfolding of the peak position (top) and of the Gaussian width (bottom), for the like-sign pairs (left) and opposite-signpairs (right), for the chain mass limit of 0.59 GeV, using the statistical errors only. The black closed points indicate the values of the fitparameter obtained from the fit of Δ3h, and the open red point is the unfolded value obtained from the HBOM fit.

M. AABOUD et al. PHYSICAL REVIEW D 96, 092008 (2017)

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of higher order and by varying the range of the fit of theΔ3hðQÞ distribution. Good stability is observed in theunfolding fit of the Gaussian functions mean and widthvalues, the results of the fit variations are compatible withinthe statistical errors, and therefore no additional systematicuncertainty is attributed to the fit procedure. It is notnecessary to unfold the normalization parameters via theHBOM method since they are fixed with much higherprecision by the adjustment of the correlation strength. Thecorrelation coefficient is −0.3 (0.5) for fitted QLS and QOS(σLS and σOS) values.

VIII. RESULTS

The value of the upper limit on the chain mass for whichthe chain selection reproduces the inclusive correlationstrength is obtained by interpolation between HBOMresults obtained by variation of the chain mass limit mcut

3hby 10 MeV (Table II).

The resulting adjusted chain mass-limit value

mcut3h ðCS ¼ CCSÞ ¼ 591� 2ðstatÞ � 7ðsystÞ MeV ð10Þ

is in agreement with the value mn¼3 ¼ 570� 20 MeVexpected by the helix fragmentation model, Eq. (2).The comparison of the corrected inclusive correlation

function ΔðQÞ with the corrected correlation functionΔ3hðQÞ representing the contribution from the chain selec-tion for the adjusted chain mass limit is shown in Fig. 7. Theregion of adjustment, indicated by the shaded area, corre-sponds to the region where the enhanced like-sign pairproduction is observed.In order to measure the shape of the correlation function

that corresponds to the adjusted chain mass limit, theunfolding of the parametrized shape of Δ3hðQÞ is repeatedfor several chainmass limit values (0.58, 0.59, and 0.6GeV),and the unfolded parameters are interpolated to the adjustedchains mass-limit value (Table III). The reconstructionsystematic uncertainty is evaluated by applying a correlatedsmearing of input bin values according to the pair-reconstruction systematic uncertainty. The variation offolding factors has a negligible impact on the shape ofthe distribution.The unfolded Δ3h measured in the chain selection with

the adjusted chain mass limit reproduces the shape of theinclusive correlation function in the low-Q region. Inaddition, good agreement is observed between the meas-urement and the helix model predictions for a chain of threeground-state pions (last column in Table III). The width ofthe peaks is not predicted by the model, although it can beassimilated with the fluctuations of the helix shape of thefield. The experimental resolution is better than 10 MeV inthe low-Q region.

A. Stability of results

The analysis was repeated using a single-Gaussianparametrization, with independent fits of the negativeand positive regions of Δ3hðQÞ. The change of the fittingfunction had no significant impact on the results. Inaddition, the analysis was repeated with HBOM foldingaccompanied by smearing of reconstructed track parame-ters according to the reconstruction uncertainty. No sig-nificant change in the results was observed.

TABLE II. The unfolded relative correlation strength CCS=CS for three values of the upper limit on the mass of the triplet chain(column 2). Interpolating between the observed values of CCS=CS, the value of mcut

3h is adjusted to yield CCS=CS ¼ 1 (column 3). Thesystematic uncertainty combines reconstruction uncertainty and the uncertainty of folding factors.

mcut3h (input)

Parameter (MeV) 580 590 600 Interpolation

CCS=CS� σðstatÞ 0.88� 0.02 0.99� 0.02 1.09� 0.02 1.00� 0.02ðstatÞ � 0.07ðsystÞmcut

3h adjusted 591� 2ðstatÞ � 7ðsystÞ

Q [GeV]

-110 1

(Q)

0

0.002

0.004

0.006-1bμ= 7 TeV, 190 sData,

inclusive

< 0.59 GeV3h

, m3h

region of adjustment

ATLAS

FIG. 7. The corrected ΔðQÞ is compared with the correctedcontribution from low-mass three-hadron chains Δ3hðQÞ. Thechain mass limit is set to a value of mcut

3h ¼ 0.59 GeV, whichreproduces the excess in the inclusive like-sign pair production atlow Q (shaded area). Bin errors indicate the combined statisticaland reconstruction uncertainty. The uncertainty of the track-basedweights is absorbed in the adjustment procedure and translatedinto uncertainty of the upper chain mass limit.

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The stability of the results was verified by a variation ofthe acceptance requirements; the pseudorapidity range wasreduced from jηj < 2.5 to jηj < 1, and in a separate study,the transverse momentum threshold was raised from 100 to200 MeV. The study of the impact of track migration acrossthe acceptance boundary was performed; a three-hadronchain containing a particle beyond the acceptance boundarywas not reconstructed, but the remaining pair contributed tothe inclusive spectrum. The fraction of lost chains wastraced and found to be 17% across the pseudorapidity limitat jηj ¼ 1 and 30% across the transverse momentum limit atpT ¼ 200 MeV. Taking into account the track migration,no significant differences were observed in the correlationshape Δ3h measured within restricted acceptance regions.The loss of chains due to a track beyond the detector

acceptance as well as the efficiency of the chain selectioncannot be fully assessed by the analysis, and the measuredchain mass limit is to be considered as an upper limit only.An estimate of the mass-limit range can be made in thereconstructed data from the rate of like-sign pairs at low Qnot associated with the chain selection (∼30%). Under thehypothesis that one-third of the unassociated like-sign pairs

belongs to nonreconstructed chains with very low mass(10%), the chain mass limit would have to be decreased by∼10 MeV to keep CS ¼ CCS (Table II). Thus, an asym-metric error of −10 MeV is added and propagated to thesystematic uncertainty of the Δ3hðQÞ parametrization.Table IV provides an overview of systematic uncertaintiesrelated to the chain selection.The variation of the acceptance requirements is also used

to examine the variation of the correlation strength withcharged-particle multiplicity in the inclusive sample, inde-pendently of the chain selection. Table V summarizes theresults. The systematic uncertainty is a combination of theuncertainty of the folding factors (5%) and the bias due tothe nonzero total charge in a reconstructed event (15%), thelatter being evaluated with help of a subsample of eventswith balanced content of positively and negatively chargedtracks. The correlation strength remains stable within therestricted pseudorapidity region, despite the sharp drop ofthe average charged-particle multiplicity (factor 0.33).Such a behavior supports the hypothesis of a lineardependence of correlations on the number of particles.The measured correlation strength corresponds to the

TABLE III. Unfolded double-Gaussian parametrization of Δ3h for a 10 MeV scan of the chain mass limit and interpolation to the bestestimate of mcut

3h [see also Eq. (10)] compared to the helix model predictions [2]. The systematic uncertainty accounts for allreconstruction effects except the uncertainty associated with track-based correction factors, which serves as input for the evaluation ofthe chains selection uncertainty (Table IV).

mcut3h (MeV)

Parameter 580 590 600 591(best estimate) QCD helix model predictions (MeV)�σðstatÞ �σðstatÞ � σðrecÞ

QLS 86.6� 0.4 89.4� 0.4 92.2� 0.4 89.7� 0.4� 1.2 91� 3σLS 41.4� 0.6 44.1� 0.6 46.5� 0.7 44.3� 0.6� 2.0 � � �QOS 248.3� 0.5 255.8� 0.5 262.9� 0.5 256.4� 0.5� 1.8 266� 8σOS 40.9� 0.5 43.9� 0.6 46.5� 0.7 44.2� 0.6� 1.5 � � �

TABLE IV. Overview of systematic uncertainties derived from the variation of the chain selection.

Systematic uncertainty (by source) (MeV)

Measured parameter Central value (MeV) Stat Reconstruction Unfolding Acceptance Combined

mcut3h 591 �2 �6 �4 −10 þ7.5=−13

QLS 89.7 �2.1 −2.8 þ2.1=−3.3σLS 44.3 �0.8 −1.0 þ0.8=−1.3QOS 256.4 �5.5 −7.3 þ5.5=−9.1σOS 44.2 �1.9 −2.6 þ1.9=−3.2

TABLE V. Variation of the charged-particle multiplicity and of the correlation strength with the change of acceptance region.Nmain

ch stands for the corrected charged-particle multiplicity in the acceptance region of the base analysis. All numbers are corrected fordetector effects.

Acceptance variations pT > 100 MeV jηj < 2.5 pT > 100 MeV jηj < 1 pT > 200 MeV jηj < 2.5

Nch=Nmainch

−RΔQ<0 dΔQ [%]

1 (by construction)1.07� 0.03ðstatÞþ0.05

−0.17 ðsystÞ0.33

1.24� 0.07ðstatÞþ0.06−0.21 ðsystÞ

0.780.56� 0.03ðstatÞþ0.03

−0.10 ðsystÞ

M. AABOUD et al. PHYSICAL REVIEW D 96, 092008 (2017)

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minimum rate of three-hadron chains per charged particlerequired to reproduce the correlation shape of the inclusiveΔðQÞ. The observed correlation strength in the baselineacceptance region is rather low, 1.1þ0.1

−0.2%, as reported inTable V. This suggests that it is sufficient to have a singlethree-pion chain in the ground state per three events togenerate enough correlations to reproduce the data.The correlation strength is reduced by a factor of 2 with

the increase of the transverse momentum threshold to200 MeV. In the minimum-bias sample, strings are orientedpredominantly along the beam axis, and therefore theobserved variation of the correlation strength suggeststhe correlated hadrons have small intrinsic pT. The quan-tized fragmentation model predicts the correlations occurbetween pions with an intrinsic transverse momentum of∼134 MeV, with respect to the string axis. The detailedverification of the low-pT dependence of the chain proper-ties is a challenging task for future studies.

B. Comparison with MC models

The comparison of the unfolded ΔðQÞ distributionwith the predictions of PYTHIA and HERWIG++ is shownin Fig. 8(a). The Lund fragmentation model and the clusterhadronization model predict a very similar distribution inthe region of interest for the current analysis (Q ≤ 0.3), andboth disagree with the data significantly. There is a closecorrespondence between the inclusive ΔðQÞ observableand the distribution of the momentum difference betweentrue adjacent pairs produced by the string fragmentation,retrieved from the PYTHIA8 event record. This is a featurediscussed in Sec. III B; the inclusive ΔðQÞ is constructed ina way which makes it suitable for the study of adjacenthadron pairs. Since the integral of ΔðQÞ is an invariant,there is a direct relation between the excess of measuredhadron pairs in the region of 0.3 < Q < 0.6 GeV, with

respect to the MC models, and the depletion atQ < 0.2 GeV. The hypothesis of a physics threshold inthe emission of adjacent hadrons offers a plausible explan-ation of the discrepancy between the data and the models.According to the MC estimates, the heavy flavor contri-bution to the low-Q spectrum is negligible.Figure 8(b) shows the comparison of the measured Δ3h

with PYTHIA and HERWIG++ predictions. PYTHIA does notdescribe the data, and the study of the event record revealsthat the shape of its prediction is dominated by chainsformed by a pair of adjacent hadrons (with oppositecharges) and a hadron originating from another string.HERWIG++ describes the chain selection much better eventhough it fails to reproduce the low-Q part of the measureddistribution. A similar observation was made in the study ofthe azimuthal ordering [6], where some observables werebetter described by HERWIG++.Given that neither of these event generators contains the

correlation effects induced by the fragmentation of thehelical QCD string, yet the data are to some extentdescribed, the presence of chains of ground-state hadronscannot be assessed from the shape of the measured Δ3halone. A further study of the properties of the selectedhadron triplets is discussed in the next section.

C. Three-body decay

The selected three-hadron chains with mass below0.59 GeV are used to fill a Dalitz plot with coordinates(X; Y) defined in Eq. (6). The measurement has the advan-tage of providing a single entry for each selected hadrontriplet (instead of three separate entries inΔ3h) and thereforeprovides more direct information than the measurement ofthe correlation shape. However, the combinatorial back-ground is no longer subtracted,whichmeans the correlationsare studied on top of a large background distribution.

Q [GeV]

0.2 0.4 0.6 0.8 1

(Q)

0

0.002

0.004

0.006

DataHerwig++

PYTHIA8

PYTHIA8, rank diff < 2

-1bμ= 7 TeV, 190sATLAS

(a)

Q [GeV]

0.1 0.2 0.3

(Q)

3h

-0.001

0

0.001

Data

Herwig++

PYTHIA8

ATLAS

-1bμ = 7 TeV, 190 s

(b)

FIG. 8. (a) The comparison between the measured inclusive ΔðQÞ and the prediction of the Lund string fragmentation model(represented by PYTHIA) and of the cluster hadronization model (represented by HERWIG++). In the Lund string fragmentation model,the inclusive Δ distribution reflects the distribution of true adjacent hadrons pairs (rank difference <2), indicated by the full line.(b) Comparison of the measured Δ3hðQÞ correlation function with a representative set of hadronization models, for the three-hadronchain selection with mass m3h < 0.59 GeV.

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The data are corrected with help of the HBOMestimate of the chain recombination and of the track-based weight factors as described in Sec. VII. Thecorrection procedure was verified with the PYTHIA6

sample. Figure 9 shows the corrected decay pattern ofselected chains in the data and the equivalent obtainedfrom the generator-level MC samples. The distributionsare normalized to the number of charged particles in thesample.

The rate of selected chains is 0.24� 0.02 per chargedparticle in the data, 0.18 in PYTHIA8, 0.20 in EPOS, and 0.28in HERWIG++. A clear enhancement is observed in the dataat large Y values, which is not reproduced by any of the MCsamples (the quantum effects affecting the hadron momentaare not included in the event generators).In order to quantify the significance of the shape

difference between the data and the MC models, theDalitz plot is split into three regions; see Fig. 10. The

FIG. 9. The Dalitz plot, Eq. (6), filled with the three-body decay pattern of the three-hadron chain selection (m3h < 0.59 GeV). Topleft: ATLAS data with detector effects unfolded. Top right: PYTHIA8 4C prediction for minimum-bias events. Bottom left: EPOSprediction for minimum-bias events. Bottom right: HERWIG++ prediction for minimum-bias events.

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

(dat

a-P

YT

HIA

8) /

-5

0

5

10

15

20I

II III

ATLAS

-1bμ=7TeV, 190sData,

< 0.59 GeV3hm

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

(dat

a-H

erw

ig+

+)

/

-5

0

5

10

15

20I

II III

ATLAS

-1bμ=7TeV, 190sData,

< 0.59 GeV3hm

FIG. 10. The significance of the difference of the Dalitz plot filled with the three-body decay pattern of chains with mass below0.59 GeV, between the data and the PYTHIA8 simulation (left) and the HERWIG++ simulation (right). The signal region I gathers chainswhere the pair of like-sign hadrons carries the least momentum difference. Region III serves as a reference for the adjustment of the MCsimulation with respect to the data.

M. AABOUD et al. PHYSICAL REVIEW D 96, 092008 (2017)

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principal signal region I gathers chains where the pair oflike-sign hadrons carries the smallest momentum differ-ence. A less pronounced but still quite significant excess isobserved in region II where it can be interpreted as asignature of a quadruplet chain containing a neutral pion(see below). The models are rescaled to reproduce the rateof selected chains in the reference region III where noenhancement is observed and where no enhancement isexpected by the quantized helix string fragmentation model(see Sec. IX). The significance of the difference betweenthe data and the MC prediction is then evaluated as thenumber of standard deviations observed, calculated fromthe statistical error and from the uncertainty associated withthe bin migration and with the X, Y dependence of track-based weights and of the presence of nonprimary tracks.The reconstruction uncertainty as well as the correlateduncertainty of folding/weighting factors are strongly corre-lated between bins and therefore absorbed in the adjustmentof the MC chain rate. The χ2 per degree of freedom forcomparison of data with PYTHIA8 is 29.1, 8.1, and 0.89 inregions I, II, and III, respectively. The comparison of datawith HERWIG++ yields similar results: χ2 per degree offreedom ¼ 20.0, 12.4, and 0.98 in regions I, II, and III,respectively. The excess in region I, which contains tripletswhere the like-sign pair of particles carries the smallestmomentum difference is 1.72� 0.05% (1.35� 0.05%) ofchains per charged particle compared to the adjustedPYTHIA8 (HERWIG++) shape. The excess in region II is0.75� 0.04% (0.97� 0.04%) of chains per charged par-ticle compared to the PYTHIA8 (HERWIG++) shape.

IX. INTERPRETATION OF MEASUREMENTSUSING THE HELIX STRING MODEL

The observations described in the previous section agreewith the hypothesis that the observed correlations reflectthe pattern of the coherent emission of hadrons from ahelical QCD string. Since the adjusted chain mass limitagrees well with the expected minimum mass for a truechain of charged pions, the position of the maximum of theΔ3hðQÞ distribution can be interpreted as the measurementof the momentum difference between adjacent opposite-sign pairs of pions with rank difference 1, while theposition of the minimum can be associated with themomentum difference between like-sign pairs of pionswith rank difference 2.

A. Onset of adjacent hadron pair production

The existence of a quantum threshold for the minimummomentum difference between adjacent hadrons is afundamental feature of the quantized fragmentation model.The data are in agreement with the prediction of a thresh-oldlike behavior: after the subtraction of selected three-hadron chains from the inclusive ΔðQÞ, there are noadjacent pairs visible in the low-Q region, up to a certain

threshold value, which depends on the assumption madeabout the length of correlated hadron chains:

ΔAðQÞ ¼ ΔðQÞ − Δ3hðQÞ; ð11Þ

ΔBðQÞ ¼ ΔðQÞ − Δ3hðQÞ − fOSðQ;QOS; σOSÞ: ð12Þ

Hypotheses A and B refer to Fig. 2. Hypothesis A describesthe chain contribution as a contribution from long unin-terrupted chains. Hypothesis B assumes the triplet chainsare disconnected and restores the contribution from oppo-site-sign pairs, which had been scaled by factor 0.5 inEq. (5), using the fitted decomposition of Δ3h into twoGaussian functions, Eq. (9).The distributions after the subtractions are shown in

Fig. 11. In the scenario of disconnected three-pion chains,the threshold value moves up to ∼0.25 GeV. This valuecoincides with the quantum threshold predicted by thequantized model of fragmentation of a helical QCD string,which also fits the experimentally found position of thepeak formed by closest opposite-sign pairs.

B. Enhanced production of pairs of like-signcharged hadrons

The enhanced production of pairs of like-sign chargedhadrons is traditionally attributed to the Bose-Einsteineffect, originating in the symmetrization of the quantum-mechanical amplitude with respect to the exchange ofidentical bosons [7]. A large number of measurements havebeen done on the basis of the correlation function definedas a ratio of like-sign and opposite-sign distributions, thelatter being considered “uncorrelated” by the Bose-Einsteinformalism.

Q [GeV]

0.1 0.2 0.3 0.4 0.5

(Q)

0

0.002

0.004

0.006 -1bμ = 7 TeV, 190sData,

(inclusive)

< 0.59 GeV3h

, mA

< 0.59 GeV3h

, mB

ATLAS

FIG. 11. The unfolded ΔðQÞ with (black points) and without(red points) the contribution from low-mass three-hadron chains.Closed squares indicate the subtraction performed assuming longuninterrupted chains (A), and open circles indicate the subtractiondone assuming disconnected triplets (B).

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Figure 12 shows the ratio R ¼ NðQÞLS=NðQÞOS beforeand after subtraction of the estimated contribution fromordered hadron chains with mass below 0.59 GeV. The

subtraction is done in close analogy to Eqs. (11) and (12)with the help of the fit [Eq. (9)],

RAðQÞ ¼ ½NðQÞLS þ NchfLSðQ;QLS; σLSÞ�=½NðQÞOS − NchfOSðQ;QOS; σOSÞ�; ð13Þ

RBðQÞ ¼ ½NðQÞLS þ NchfLSðQ;QLS; σLSÞ�=½NðQÞOS − 2NchfOSðQ;QOS; σOSÞ�; ð14Þ

i.e. the Δ3h distribution is decomposed into contributionsfrom like-sign and opposite-sign pairs, which are sub-tracted from their respective inclusive two-particle distri-butions, before calculating the ratio. The subtraction isdone for the hypothesis of long chains [A] (open red points)and disconnected chains [B] (closed red points). In bothcases, the chain selection contains the source of theenhanced like-sign pair production, hence providing analternative explanation of the data.

C. Three-body decay properties ofquantized fragmentation

Figure 13 compares the measured three-body decaypattern of the chain selection with the model predictionobtained by generating hadron triplets and quadruplets

Q [GeV]0.2 0.4 0.6 0.8 1

R(Q

)

0.9

1

1.1

1.2-1bμ = 7 TeV, 190 sData,

R (inclusive)

3h, m < 0.59 GeVAR

3h, m < 0.59 GeVBR

ATLAS

FIG. 12. The ratio of inclusive like-sign and opposite-sign pairspectra, before and after subtraction of the estimated contributionfrom low-mass three-hadron chains, in scenario A (long unin-terrupted chain) and B (disconnected triplet chains). The uppermass limit for the three-hadron chain (0.59 GeV) has been set tothe value that reproduces the enhancement of like-sign pairproduction in the inclusive sample.

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

chains-+- and +-+expected signal from

0.05± = 2.80

4 MeV±R = 68

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

chains-)+(-+ and -+)-(+expected signal from

0.05± = 2.80

4 MeV±R = 68

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

chains-+0- and +0-+expected signal from

0.05± = 2.80

4 MeV±R = 68

X

-1 -0.5 0 0.5 1

Y

-1

-0.5

0

0.5

1

ch /

N3h

N

0

0.0005

0.001

ATLAS

-1bμ=7 TeV, 190 sData,

<0.59 GeV3hm

predictionmodel

FIG. 13. Model prediction for the decay pattern of the ground-state triplet (top left), ground-state quadruplet with a missing middlemember (top right), and ground-state quadruplet containing a neutral pion (bottom left), in an arbitrary z scale. Model predictions arecalculated using a Gaussian smearing of helical string parameters constrained by the fit of the mass spectrum of pseudoscalar mesons.The resolution uncertainty of the order of 10 MeV is included in the variation of string parameters. Bottom right: Comparison of theobserved chain decay pattern with model predictions.

M. AABOUD et al. PHYSICAL REVIEW D 96, 092008 (2017)

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according to the pattern of helical string fragmentation intochains of ground-state pions (see the Appendix). Stringparameters ΔΦ and κR are smeared by 2% and 6%,respectively. The maximal enhancement in the data corre-sponds to the expected location of the signal from the chainof three ground-state pions, with some indication for thepossible presence of quadruplet chains; the wide “shoulder”of the signal in region I can be interpreted as a signature of aquadruplet chain with a missing middle particle. Theobservation of such a form of signal has implications forthe interpretation of the results of the measurements. If thereis a significant admixture of opposite-sign pairs with rankdifference 3 (for which the momentum difference should bearound 0.236 GeV), the bias should be taken into account inthe interpretation of results in terms of properties of theQCDstring. This bias is obtained from the best fit of theDalitz plotwith the mixture of the PYTHIA6 shape (for background) andfrom the model predictions for the triplet and for theincomplete-quadruplet chains (for the signal) and foundto be−9� 5 MeV.The uncertainty is estimated as one-thirdof the case, where the selection is equally spread betweenpairs with rank differences 1 and 3.As described in the Introduction, the quantized helical

string fragmentation model draws input from the massspectrum of light pseudoscalar mesons. It is thereforepossible that their decay contributes to the visible corre-lation pattern, but such a measurement would require thereconstruction of π0 and therefore falls beyond the scope ofthe current analysis.

D. Momentum difference as a function ofhadron rank difference

Taking into account the uncertainty of the chain selection(Table IV), the inclusive two-particle correlation pattern isreproduced by three-hadron chains below a mass limit of

mcut3h ¼ 591� 2ðstatÞþ7.5

−13 ðsystÞ MeV: ð15Þ

The data show a threshold effect in the production ofadjacent hadron pairs. The threshold coincides with theemergence of the Gaussian peak situated at

QOS ¼ 256.4� 0.5ðstatÞ� 1.8ðrecÞþ5.5

−9.1ðchain selectionÞ MeV; ð16Þ

which is obtained from the fit of the preferred momentumdifference between opposite-sign pairs in the selectedchains. Taking into account the possible admixture of pairswith rank difference 3, suggested by the particular form ofthe three-body decay pattern of selected hadron chains, thebest estimate of the momentum difference for hadron pairsof rank difference r ¼ 1 becomes

Qðr ¼ 1Þ ¼ 265.6� 0.5ðstatÞ� 1.8ðrecÞþ7.4

−10 ðchain selectionÞ MeV: ð17ÞThe preferred momentum difference between hadrons

with like-sign charge combination (rank difference r ¼ 2)is found to be

Qðr ¼ 2Þ ¼ 89.7� 0.4ðstatÞ� 1.2ðrecÞþ2.1

−3.3ðchain selectionÞ MeV ð18Þ

for the same set of selected three-hadron chains. Both like-sign and opposite-sign pair distributions have a Gaussianshape with a width of 44� 3 MeV, while the experimentalresolution in the fitted region is better than 10 MeV.The systematic uncertainties in Eqs. (17) and (18) arecorrelated.These values are in good agreement with the predictions

of the model of a QCD string with a helical shape, withparameters constrained by the mass spectrum of pseudo-scalar mesons (see Table I).

X. CONCLUSIONS

Two-particle correlation spectra measured in theminimum-bias sample at a center-of-mass energy of7 TeV are analyzed in the context of coherent particleproduction. The data sample consists of 190 μb−1 of eventsproduced with low-luminosity proton-proton beams at theLHC and collected in the early 2010 ATLAS data taking.The QCD string fragmentation scenario is used to introducethe notion of ordered hadron chains. Using the assumptionof the local charge conservation in the string breakup, thecorrelation function is defined in a way suitable for study ofcorrelations between pairs and triplets of adjacent hadrons.Because it is experimentally impossible to assess the exactrank ordering of particles, the rank ordering is replaced bythe minimization of the mass of hadron chains. Theanalysis relies on the removal of the background of randomcombinations by means of the subtraction of pairs withlike-sign charge combination from pairs with opposite-signcharge combination. The analysis does not rely on pre-dictions of conventional MC models which fail to describethe data.The results indicate that the enhanced like-sign pair

production at low Q, observed in the data and traditionallyattributed to the Bose-Einstein effect, can be entirelyattributed to the presence of ordered three-hadron chainswith mass below 591þ8

−13 MeV, at a minimum rate of1.1þ0.1

−0.2% per charged particle. A strong dependence ofthe size of the effect on the transverse momentum of tracksin the laboratory frame is observed.The shape of the three-hadron chain contribution to the

inclusive Q spectra agrees with the hypothesis that thesechains are produced via coherent quantized fragmentationof a homogeneous QCD string with a helical structure.

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The measured momentum difference between hadronswithin such a chain is 89.7þ2.5

−3.5 MeV for pairs with rankdifference 2 and 266þ8

−11 MeV for pairs of adjacenthadrons. The data support the prediction of a “forbidden”region for the production of adjacent (opposite-sign)hadron pairs at low Q. The threshold is situated at∼0.25 GeV and agrees with the quantum threshold pre-dicted by the helical string model.

ACKNOWLEDGMENTS

We thank CERN for the very successful operation ofthe LHC as well as the support staff from our institutions,without whom ATLAS could not be operated efficiently.We acknowledge the support of ANPCyT, Argentina;YerPhI, Armenia; ARC, Australia; BMWFW and FWF,Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq andFAPESP, Brazil; NSERC, NRC, and CFI, Canada;CERN; CONICYT, Chile; CAS, MOST, and NSFC,China; COLCIENCIAS, Colombia; MSMT CR, MPOCR, and VSC CR, Czech Republic; DNRF and DNSRC,Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France;SRNSF, Georgia; BMBF, HGF, and MPG, Germany;GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE, and Benoziyo Center, Israel; INFN, Italy; MEXTand JSPS, Japan; CNRST, Morocco; NWO, Netherlands;RCN, Norway; MNiSW and NCN, Poland; FCT,Portugal; MNE/IFA, Romania; MES of Russia andNRC KI, Russian Federation; JINR; MESTD, Serbia;MSSR, Slovakia; ARRS and MIZŠ, Slovenia; DST/NRF,South Africa; MINECO, Spain; SRC and WallenbergFoundation, Sweden; SERI, SNSF, and Cantons of Bernand Geneva, Switzerland; MOST, Taiwan; TAEK,Turkey; STFC, United Kingdom; and DOE and NSF,U.S.. In addition, individual groups and members havereceived support from BCKDF, the Canada Council,CANARIE, CRC, Compute Canada, FQRNT, and theOntario Innovation Trust, Canada; EPLANET, ERC,ERDF, FP7, Horizon 2020, and Marie Skłodowska-Curie Actions, European Union; Investissementsd’Avenir Labex and Idex, ANR, Region Auvergne andFondation Partager le Savoir, France; DFG and AvHFoundation, Germany; Herakleitos, Thales and Aristeiaprograms cofinanced by EU-ESF and the GreekNSRF; BSF, GIF and Minerva, Israel; BRF, Norway;CERCA Programme Generalitat de Catalunya,Generalitat Valenciana, Spain; and the Royal Societyand Leverhulme Trust, United Kingdom. The crucialcomputing support from all WLCG partners is acknowl-edged gratefully, in particular from CERN, the ATLASTier-1 facilities at TRIUMF (Canada), NDGF (Denmark,Norway, Sweden), CC-IN2P3 (France), KIT/GridKA(Germany), INFN-CNAF (Italy), NL-T1 (Netherlands),PIC (Spain), ASGC (Taiwan), RAL (United Kingdom)and BNL (U.S.), the Tier-2 facilities worldwide and large

non-WLCG resource providers. Major contributors ofcomputing resources are listed in Ref. [22].

APPENDIX: CALCULATION OF PREDICTIONSWITHIN THE HELICAL QCD STRING MODEL

In the model described in Ref. [2], the causal constraintapplied to the helical QCD field leads to a quantizationpattern describing the mass spectrum of hadrons with massbelow 1 GeV. In particular, the pseudoscalar mesons(π; η; η0) can be regarded as string pieces fragmenting into(n ¼ 1, 3, 5) ground-state hadrons (pions), with transverseenergy (ET) and momentum (pT) of mesons defined by thehelical string properties (Fig. 1),

ETðnÞ ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffim2

n þ pTðnÞ2q

¼ nκRΔΦ; ðA1Þ

where R stands for the radius of the helix, κ ∼ 1 GeV=fmis the string tension, ΔΦ is the quantized helix phasedifference describing the shortest piece of string that canform a hadron, and mn is the (quantized) meson massspectrum.The transverse momentum of a hadron stems from the

integral of the string tension along the trajectory (in thetransverse plane) of a quark traveling from one breakupvertex to another. The string tension is tangential to thetrajectory of the quark:

pTðΦ;Φþ nΔΦÞ

¼ ðpxT; ip

yTÞ ¼ κR

ZΦþnΔΦ

Φeiðαþπ

2Þdα

¼ 2κR sinnΔΦ2

eiðΦþnΔΦ2þπ

2Þ: ðA2Þ

The fit of the mass spectrum of pseudoscalar mesonsindicates a rather narrow radius of the helical string(κR ¼ 68� 2 MeV) and a quantized phase differenceΔΦ ¼ 2.82� 0.06. These values translate into the quan-tized ground-state transverse energy, ETðn¼1Þ≃192MeV,and the transverse momentum of a ground-state pion,pTðn ¼ 1Þ≃ 134 MeV [2].When a piece of helical string fragments into a chain of

ground-state pions, the string shape is reflected in themomentum difference of the emitted hadrons. Neglectingthe longitudinal momentum differences between adjacenthadrons i.e. assuming local homogeneity of the fragment-ing QCD field, the four-momentum difference betweenhadrons within a chain of ground-state pions can be writtenas a function of their rank difference r,

QðrÞ ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi−ðpi − piþrÞ2

q¼ 2pTðn ¼ 1Þjsin ðrΔΦ=2Þj;

ðA3Þ

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where rΔΦ corresponds to the opening angle betweenpions in the transverse plane. Equation (A3) is used to fillTable I.It is straightforward to calculate the (transverse)

momenta of pions in the chain defined by string breakupvertices Φjþ1 ¼ Φj þ ΔΦ;…;Φjþn ¼ Φj þ nΔΦ, and tostudy the properties of pion multiplets for various rankdifference combinations. A closer look at Table I suggeststhe minimization of the mass of selected three-hadronclusters does not ensure the selection of a triplet of adjacentpions in case of the presence of a longer chain. The largestcontamination presumably comes from an incompletequadruplet chain with a missing (internal) pion and froma quadruplet chain containing a neutral pion. Quadrupletchains are therefore included as a correction to the modelpredictions. For the study of three-body decays, pions inselected triplets are boosted into the rest frame of the triplet,and their kinetic energy is evaluated (the longitudinalmomenta of triplet members are negligible in the restframe of the triplet).The helix-string model predictions for triplets of charged

pions composed of particles with rank difference r < 4 areshown in Fig. 13, using a numerical smearing of themeasured parameters κR and ΔΦ (by a Gaussian distribu-tion with a width of 6% and 2%, respectively). Figure 14shows the corresponding shapes of the correlation functionΔ3hðQÞ. The presence of a pair with rank difference 3modifies the shape of the positive part of the Δ3h distri-bution. The presence of a neutral pion within the chain

tends to diminish the correlation signal by compensating, tosome extent, the asymmetry between the like-sign and theopposite-sign pair Q distributions.

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Q [GeV]0 0.1 0.2 0.3 0.4 0.5

(Q)

3hΔ

-0.1

0

0.1

-310×

model expectation

-π+π-π / +π-π+π-π)+π(-π+π / -π+π)-π(+π

-π+π0π-π / +π0π-π+π

.05±=2.80ΦΔ

4 MeV±R=68κ

FIG. 14. Evaluation of the model prediction for the shape of thecorrelation function Δ3h produced by the ground-state triplet(black points), ground-state quadruplet with a missing middlemember (blue points), and ground-state quadruplet containing aneutral pion (red points), for an equal number of triplets of eachtype. Model predictions are calculated using a Gaussian smearingof helical string parameters constrained by the fit of the massspectrum of pseudoscalar mesons. The resolution uncertainty ofthe order of 10 MeV is included in the variation of stringparameters.

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R. Cardarelli,135a F. Cardillo,51 I. Carli,131 T. Carli,32 G. Carlino,106a B. T. Carlson,127 L. Carminati,94a,94b

R. M. D. Carney,148a,148b S. Caron,108 E. Carquin,34b S. Carrá,94a,94b G. D. Carrillo-Montoya,32 D. Casadei,19

M. P. Casado,13,k M. Casolino,13 D.W. Casper,166 R. Castelijn,109 V. Castillo Gimenez,170 N. F. Castro,128a,l A. Catinaccio,32

J. R. Catmore,121 A. Cattai,32 J. Caudron,23 V. Cavaliere,169 E. Cavallaro,13 D. Cavalli,94a M. Cavalli-Sforza,13

V. Cavasinni,126a,126b E. Celebi,20a F. Ceradini,136a,136b L. Cerda Alberich,170 A. S. Cerqueira,26b A. Cerri,151

L. Cerrito,135a,135b F. Cerutti,16 A. Cervelli,18 S. A. Cetin,20c A. Chafaq,137a D. Chakraborty,110 S. K. Chan,59 W. S. Chan,109

Y. L. Chan,62a P. Chang,169 J. D. Chapman,30 D. G. Charlton,19 C. C. Chau,31 C. A. Chavez Barajas,151 S. Che,113

S. Cheatham,167a,167c A. Chegwidden,93 S. Chekanov,6 S. V. Chekulaev,163a G. A. Chelkov,68,m M. A. Chelstowska,32

C. Chen,67 H. Chen,27 J. Chen,36a S. Chen,35b S. Chen,157 X. Chen,35c,n Y. Chen,70 H. C. Cheng,92 H. J. Cheng,35a

A. Cheplakov,68 E. Cheremushkina,132 R. Cherkaoui El Moursli,137e E. Cheu,7 K. Cheung,63 L. Chevalier,138 V. Chiarella,50

G. Chiarelli,126a,126b G. Chiodini,76a A. S. Chisholm,32 A. Chitan,28b Y. H. Chiu,172 M. V. Chizhov,68 K. Choi,64

A. R. Chomont,37 S. Chouridou,156 Y. S. Chow,62a V. Christodoulou,81 M. C. Chu,62a J. Chudoba,129 A. J. Chuinard,90

J. J. Chwastowski,42 L. Chytka,117 A. K. Ciftci,4a D. Cinca,46 V. Cindro,78 I. A. Cioara,23 C. Ciocca,22a,22b A. Ciocio,16

F. Cirotto,106a,106b Z. H. Citron,175 M. Citterio,94a M. Ciubancan,28b A. Clark,52 B. L. Clark,59 M. R. Clark,38 P. J. Clark,49

R. N. Clarke,16 C. Clement,148a,148b Y. Coadou,88 M. Cobal,167a,167c A. Coccaro,52 J. Cochran,67 L. Colasurdo,108 B. Cole,38

A. P. Colijn,109 J. Collot,58 T. Colombo,166 P. Conde Muiño,128a,128b E. Coniavitis,51 S. H. Connell,147b I. A. Connelly,87

S. Constantinescu,28b G. Conti,32 F. Conventi,106a,o M. Cooke,16 A. M. Cooper-Sarkar,122 F. Cormier,171 K. J. R. Cormier,161

M. Corradi,134a,134b F. Corriveau,90,p A. Cortes-Gonzalez,32 G. Cortiana,103 G. Costa,94a M. J. Costa,170 D. Costanzo,141

G. Cottin,30 G. Cowan,80 B. E. Cox,87 K. Cranmer,112 S. J. Crawley,56 R. A. Creager,124 G. Cree,31 S. Crepe-Renaudin,58

F. Crescioli,83 W. A. Cribbs,148a,148b M. Cristinziani,23 V. Croft,108 G. Crosetti,40a,40b A. Cueto,85

T. Cuhadar Donszelmann,141 A. R. Cukierman,145 J. Cummings,179 M. Curatolo,50 J. Cúth,86 S. Czekierda,42

P. Czodrowski,32 G. D’amen,22a,22b S. D’Auria,56 L. D’eramo,83 M. D’Onofrio,77 M. J. Da Cunha Sargedas De Sousa,128a,128b

C. Da Via,87 W. Dabrowski,41a T. Dado,146a T. Dai,92 O. Dale,15 F. Dallaire,97 C. Dallapiccola,89 M. Dam,39 J. R. Dandoy,124

M. F. Daneri,29 N. P. Dang,176 A. C. Daniells,19 N. S. Dann,87 M. Danninger,171 M. Dano Hoffmann,138 V. Dao,150

G. Darbo,53a S. Darmora,8 J. Dassoulas,3 A. Dattagupta,118 T. Daubney,45 W. Davey,23 C. David,45 T. Davidek,131

D. R. Davis,48 P. Davison,81 E. Dawe,91 I. Dawson,141 K. De,8 R. de Asmundis,106a A. De Benedetti,115 S. De Castro,22a,22b

S. De Cecco,83 N. De Groot,108 P. de Jong,109 H. De la Torre,93 F. De Lorenzi,67 A. De Maria,57 D. De Pedis,134a

A. De Salvo,134a U. De Sanctis,135a,135b A. De Santo,151 K. De Vasconcelos Corga,88 J. B. De Vivie De Regie,119 R. Debbe,27

C. Debenedetti,139 D. V. Dedovich,68 N. Dehghanian,3 I. Deigaard,109 M. Del Gaudio,40a,40b J. Del Peso,85 D. Delgove,119

F. Deliot,138 C. M. Delitzsch,7 A. Dell’Acqua,32 L. Dell’Asta,24 M. Dell’Orso,126a,126b M. Della Pietra,106a,106b

D. della Volpe,52 M. Delmastro,5 C. Delporte,119 P. A. Delsart,58 D. A. DeMarco,161 S. Demers,179 M. Demichev,68

A. Demilly,83 S. P. Denisov,132 D. Denysiuk,138 D. Derendarz,42 J. E. Derkaoui,137d F. Derue,83 P. Dervan,77 K. Desch,23

C. Deterre,45 K. Dette,161 M. R. Devesa,29 P. O. Deviveiros,32 A. Dewhurst,133 S. Dhaliwal,25 F. A. Di Bello,52

A. Di Ciaccio,135a,135b L. Di Ciaccio,5 W. K. Di Clemente,124 C. Di Donato,106a,106b A. Di Girolamo,32 B. Di Girolamo,32

B. Di Micco,136a,136b R. Di Nardo,32 K. F. Di Petrillo,59 A. Di Simone,51 R. Di Sipio,161 D. Di Valentino,31 C. Diaconu,88

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M. Diamond,161 F. A. Dias,39 M. A. Diaz,34a E. B. Diehl,92 J. Dietrich,17 S. Díez Cornell,45 A. Dimitrievska,14

J. Dingfelder,23 P. Dita,28b S. Dita,28b F. Dittus,32 F. Djama,88 T. Djobava,54b J. I. Djuvsland,60a M. A. B. do Vale,26c

D. Dobos,32 M. Dobre,28b C. Doglioni,84 J. Dolejsi,131 Z. Dolezal,131 M. Donadelli,26d S. Donati,126a,126b P. Dondero,123a,123b

J. Donini,37 J. Dopke,133 A. Doria,106a M. T. Dova,74 A. T. Doyle,56 E. Drechsler,57 M. Dris,10 Y. Du,36b

J. Duarte-Campderros,155 A. Dubreuil,52 E. Duchovni,175 G. Duckeck,102 A. Ducourthial,83 O. A. Ducu,97,q D. Duda,109

A. Dudarev,32 A. Chr. Dudder,86 E. M. Duffield,16 L. Duflot,119 M. Dührssen,32 M. Dumancic,175 A. E. Dumitriu,28b

A. K. Duncan,56 M. Dunford,60a H. Duran Yildiz,4a M. Düren,55 A. Durglishvili,54b D. Duschinger,47 B. Dutta,45

M. Dyndal,45 B. S. Dziedzic,42 C. Eckardt,45 K. M. Ecker,103 R. C. Edgar,92 T. Eifert,32 G. Eigen,15 K. Einsweiler,16

T. Ekelof,168 M. El Kacimi,137c R. El Kosseifi,88 V. Ellajosyula,88 M. Ellert,168 S. Elles,5 F. Ellinghaus,178 A. A. Elliot,172

N. Ellis,32 J. Elmsheuser,27 M. Elsing,32 D. Emeliyanov,133 Y. Enari,157 O. C. Endner,86 J. S. Ennis,173 J. Erdmann,46

A. Ereditato,18 M. Ernst,27 S. Errede,169 M. Escalier,119 C. Escobar,170 B. Esposito,50 O. Estrada Pastor,170 A. I. Etienvre,138

E. Etzion,155 H. Evans,64 A. Ezhilov,125 M. Ezzi,137e F. Fabbri,22a,22b L. Fabbri,22a,22b V. Fabiani,108 G. Facini,81

R. M. Fakhrutdinov,132 S. Falciano,134a R. J. Falla,81 J. Faltova,32 Y. Fang,35a M. Fanti,94a,94b A. Farbin,8 A. Farilla,136a

C. Farina,127 E. M. Farina,123a,123b T. Farooque,93 S. Farrell,16 S. M. Farrington,173 P. Farthouat,32 F. Fassi,137e P. Fassnacht,32

D. Fassouliotis,9 M. Faucci Giannelli,80 A. Favareto,53a,53b W. J. Fawcett,122 L. Fayard,119 O. L. Fedin,125,r W. Fedorko,171

S. Feigl,121 L. Feligioni,88 C. Feng,36b E. J. Feng,32 H. Feng,92 M. J. Fenton,56 A. B. Fenyuk,132 L. Feremenga,8

P. Fernandez Martinez,170 S. Fernandez Perez,13 J. Ferrando,45 A. Ferrari,168 P. Ferrari,109 R. Ferrari,123a

D. E. Ferreira de Lima,60b A. Ferrer,170 D. Ferrere,52 C. Ferretti,92 F. Fiedler,86 A. Filipčič,78 M. Filipuzzi,45 F. Filthaut,108

M. Fincke-Keeler,172 K. D. Finelli,152 M. C. N. Fiolhais,128a,128c,s L. Fiorini,170 A. Fischer,2 C. Fischer,13 J. Fischer,178

W. C. Fisher,93 N. Flaschel,45 I. Fleck,143 P. Fleischmann,92 R. R. M. Fletcher,124 T. Flick,178 B. M. Flierl,102

L. R. Flores Castillo,62a M. J. Flowerdew,103 G. T. Forcolin,87 A. Formica,138 F. A. Förster,13 A. Forti,87 A. G. Foster,19

D. Fournier,119 H. Fox,75 S. Fracchia,141 P. Francavilla,83 M. Franchini,22a,22b S. Franchino,60a D. Francis,32 L. Franconi,121

M. Franklin,59 M. Frate,166 M. Fraternali,123a,123b D. Freeborn,81 S. M. Fressard-Batraneanu,32 B. Freund,97 D. Froidevaux,32

J. A. Frost,122 C. Fukunaga,158 T. Fusayasu,104 J. Fuster,170 C. Gabaldon,58 O. Gabizon,154 A. Gabrielli,22a,22b A. Gabrielli,16

G. P. Gach,41a S. Gadatsch,32 S. Gadomski,80 G. Gagliardi,53a,53b L. G. Gagnon,97 C. Galea,108 B. Galhardo,128a,128c

E. J. Gallas,122 B. J. Gallop,133 P. Gallus,130 G. Galster,39 K. K. Gan,113 S. Ganguly,37 Y. Gao,77 Y. S. Gao,145,h

F. M. Garay Walls,49 C. García,170 J. E. García Navarro,170 J. A. García Pascual,35a M. Garcia-Sciveres,16 R.W. Gardner,33

N. Garelli,145 V. Garonne,121 A. Gascon Bravo,45 K. Gasnikova,45 C. Gatti,50 A. Gaudiello,53a,53b G. Gaudio,123a

I. L. Gavrilenko,98 C. Gay,171 G. Gaycken,23 E. N. Gazis,10 C. N. P. Gee,133 J. Geisen,57 M. Geisen,86 M. P. Geisler,60a

K. Gellerstedt,148a,148b C. Gemme,53a M. H. Genest,58 C. Geng,92 S. Gentile,134a,134b C. Gentsos,156 S. George,80

D. Gerbaudo,13 A. Gershon,155 G. Geßner,46 S. Ghasemi,143 M. Ghneimat,23 B. Giacobbe,22a S. Giagu,134a,134b

N. Giangiacomi,22a,22b P. Giannetti,126a,126b S. M. Gibson,80 M. Gignac,171 M. Gilchriese,16 D. Gillberg,31 G. Gilles,178

D. M. Gingrich,3,e M. P. Giordani,167a,167c F. M. Giorgi,22a P. F. Giraud,138 P. Giromini,59 G. Giugliarelli,167a,167c D. Giugni,94a

F. Giuli,122 C. Giuliani,103 M. Giulini,60b B. K. Gjelsten,121 S. Gkaitatzis,156 I. Gkialas,9,t E. L. Gkougkousis,13

P. Gkountoumis,10 L. K. Gladilin,101 C. Glasman,85 J. Glatzer,13 P. C. F. Glaysher,45 A. Glazov,45 M. Goblirsch-Kolb,25

J. Godlewski,42 S. Goldfarb,91 T. Golling,52 D. Golubkov,132 A. Gomes,128a,128b,128d R. Gonçalo,128a R. Goncalves Gama,26a

J. Goncalves Pinto Firmino Da Costa,138 G. Gonella,51 L. Gonella,19 A. Gongadze,68 S. González de la Hoz,170

S. Gonzalez-Sevilla,52 L. Goossens,32 P. A. Gorbounov,99 H. A. Gordon,27 I. Gorelov,107 B. Gorini,32 E. Gorini,76a,76b

A. Gorišek,78 A. T. Goshaw,48 C. Gössling,46 M. I. Gostkin,68 C. A. Gottardo,23 C. R. Goudet,119 D. Goujdami,137c

A. G. Goussiou,140 N. Govender,147b,u E. Gozani,154 L. Graber,57 I. Grabowska-Bold,41a P. O. J. Gradin,168 J. Gramling,166

E. Gramstad,121 S. Grancagnolo,17 V. Gratchev,125 P. M. Gravila,28f C. Gray,56 H. M. Gray,16 Z. D. Greenwood,82,v

C. Grefe,23 K. Gregersen,81 I. M. Gregor,45 P. Grenier,145 K. Grevtsov,5 J. Griffiths,8 A. A. Grillo,139 K. Grimm,75

S. Grinstein,13,w Ph. Gris,37 J.-F. Grivaz,119 S. Groh,86 E. Gross,175 J. Grosse-Knetter,57 G. C. Grossi,82 Z. J. Grout,81

A. Grummer,107 L. Guan,92 W. Guan,176 J. Guenther,65 F. Guescini,163a D. Guest,166 O. Gueta,155 B. Gui,113 E. Guido,53a,53b

T. Guillemin,5 S. Guindon,2 U. Gul,56 C. Gumpert,32 J. Guo,36c W. Guo,92 Y. Guo,36a R. Gupta,43 S. Gupta,122

G. Gustavino,115 B. J. Gutelman,154 P. Gutierrez,115 N. G. Gutierrez Ortiz,81 C. Gutschow,81 C. Guyot,138 M. P. Guzik,41a

C. Gwenlan,122 C. B. Gwilliam,77 A. Haas,112 C. Haber,16 H. K. Hadavand,8 N. Haddad,137e A. Hadef,88 S. Hageböck,23

M. Hagihara,164 H. Hakobyan,180,a M. Haleem,45 J. Haley,116 G. Halladjian,93 G. D. Hallewell,88 K. Hamacher,178

P. Hamal,117 K. Hamano,172 A. Hamilton,147a G. N. Hamity,141 P. G. Hamnett,45 L. Han,36a S. Han,35a K. Hanagaki,69,x

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K. Hanawa,157 M. Hance,139 B. Haney,124 P. Hanke,60a J. B. Hansen,39 J. D. Hansen,39 M. C. Hansen,23 P. H. Hansen,39

K. Hara,164 A. S. Hard,176 T. Harenberg,178 F. Hariri,119 S. Harkusha,95 R. D. Harrington,49 P. F. Harrison,173

N. M. Hartmann,102 Y. Hasegawa,142 A. Hasib,49 S. Hassani,138 S. Haug,18 R. Hauser,93 L. Hauswald,47 L. B. Havener,38

M. Havranek,130 C. M. Hawkes,19 R. J. Hawkings,32 D. Hayakawa,159 D. Hayden,93 C. P. Hays,122 J. M. Hays,79

H. S. Hayward,77 S. J. Haywood,133 S. J. Head,19 T. Heck,86 V. Hedberg,84 L. Heelan,8 S. Heer,23 K. K. Heidegger,51

S. Heim,45 T. Heim,16 B. Heinemann,45,y J. J. Heinrich,102 L. Heinrich,112 C. Heinz,55 J. Hejbal,129 L. Helary,32 A. Held,171

S. Hellman,148a,148b C. Helsens,32 R. C.W. Henderson,75 Y. Heng,176 S. Henkelmann,171 A. M. Henriques Correia,32

S. Henrot-Versille,119 G. H. Herbert,17 H. Herde,25 V. Herget,177 Y. Hernández Jimenez,147c H. Herr,86 G. Herten,51

R. Hertenberger,102 L. Hervas,32 T. C. Herwig,124 G. G. Hesketh,81 N. P. Hessey,163a J. W. Hetherly,43 S. Higashino,69

E. Higón-Rodriguez,170 K. Hildebrand,33 E. Hill,172 J. C. Hill,30 K. H. Hiller,45 S. J. Hillier,19 M. Hils,47 I. Hinchliffe,16

M. Hirose,51 D. Hirschbuehl,178 B. Hiti,78 O. Hladik,129 X. Hoad,49 J. Hobbs,150 N. Hod,163a M. C. Hodgkinson,141

P. Hodgson,141 A. Hoecker,32 M. R. Hoeferkamp,107 F. Hoenig,102 D. Hohn,23 T. R. Holmes,33 M. Homann,46 S. Honda,164

T. Honda,69 T. M. Hong,127 B. H. Hooberman,169 W. H. Hopkins,118 Y. Horii,105 A. J. Horton,144 J-Y. Hostachy,58 S. Hou,153

A. Hoummada,137a J. Howarth,87 J. Hoya,74 M. Hrabovsky,117 J. Hrdinka,32 I. Hristova,17 J. Hrivnac,119 T. Hryn’ova,5

A. Hrynevich,96 P. J. Hsu,63 S.-C. Hsu,140 Q. Hu,36a S. Hu,36c Y. Huang,35a Z. Hubacek,130 F. Hubaut,88 F. Huegging,23

T. B. Huffman,122 E.W. Hughes,38 G. Hughes,75 M. Huhtinen,32 P. Huo,150 N. Huseynov,68,c J. Huston,93 J. Huth,59

G. Iacobucci,52 G. Iakovidis,27 I. Ibragimov,143 L. Iconomidou-Fayard,119 Z. Idrissi,137e P. Iengo,32 O. Igonkina,109,z

T. Iizawa,174 Y. Ikegami,69 M. Ikeno,69 Y. Ilchenko,11,aa D. Iliadis,156 N. Ilic,145 G. Introzzi,123a,123b P. Ioannou,9,a

M. Iodice,136a K. Iordanidou,38 V. Ippolito,59 M. F. Isacson,168 N. Ishijima,120 M. Ishino,157 M. Ishitsuka,159 C. Issever,122

S. Istin,20a F. Ito,164 J. M. Iturbe Ponce,62a R. Iuppa,162a,162b H. Iwasaki,69 J. M. Izen,44 V. Izzo,106a S. Jabbar,3 P. Jackson,1

R. M. Jacobs,23 V. Jain,2 K. B. Jakobi,86 K. Jakobs,51 S. Jakobsen,65 T. Jakoubek,129 D. O. Jamin,116 D. K. Jana,82

R. Jansky,52 J. Janssen,23 M. Janus,57 P. A. Janus,41a G. Jarlskog,84 N. Javadov,68,c T. Javůrek,51 M. Javurkova,51

F. Jeanneau,138 L. Jeanty,16 J. Jejelava,54a,bb A. Jelinskas,173 P. Jenni,51,cc C. Jeske,173 S. Jezequel,5 H. Ji,176 J. Jia,150

H. Jiang,67 Y. Jiang,36a Z. Jiang,145 S. Jiggins,81 J. Jimenez Pena,170 S. Jin,35a A. Jinaru,28b O. Jinnouchi,159 H. Jivan,147c

P. Johansson,141 K. A. Johns,7 C. A. Johnson,64 W. J. Johnson,140 K. Jon-And,148a,148b R.W. L. Jones,75 S. D. Jones,151

S. Jones,7 T. J. Jones,77 J. Jongmanns,60a P. M. Jorge,128a,128b J. Jovicevic,163a X. Ju,176 A. Juste Rozas,13,w M. K. Köhler,175

A. Kaczmarska,42 M. Kado,119 H. Kagan,113 M. Kagan,145 S. J. Kahn,88 T. Kaji,174 E. Kajomovitz,48 C.W. Kalderon,84

A. Kaluza,86 S. Kama,43 A. Kamenshchikov,132 N. Kanaya,157 L. Kanjir,78 V. A. Kantserov,100 J. Kanzaki,69 B. Kaplan,112

L. S. Kaplan,176 D. Kar,147c K. Karakostas,10 N. Karastathis,10 M. J. Kareem,57 E. Karentzos,10 S. N. Karpov,68

Z. M. Karpova,68 K. Karthik,112 V. Kartvelishvili,75 A. N. Karyukhin,132 K. Kasahara,164 L. Kashif,176 R. D. Kass,113

A. Kastanas,149 Y. Kataoka,157 C. Kato,157 A. Katre,52 J. Katzy,45 K. Kawade,70 K. Kawagoe,73 T. Kawamoto,157

G. Kawamura,57 E. F. Kay,77 V. F. Kazanin,111,d R. Keeler,172 R. Kehoe,43 J. S. Keller,31 E. Kellermann,84 J. J. Kempster,80

J Kendrick,19 H. Keoshkerian,161 O. Kepka,129 B. P. Kerševan,78 S. Kersten,178 R. A. Keyes,90 M. Khader,169

F. Khalil-zada,12 A. Khanov,116 A. G. Kharlamov,111,d T. Kharlamova,111,d A. Khodinov,160 T. J. Khoo,52 V. Khovanskiy,99,a

E. Khramov,68 J. Khubua,54b,dd S. Kido,70 C. R. Kilby,80 H. Y. Kim,8 S. H. Kim,164 Y. K. Kim,33 N. Kimura,156 O. M. Kind,17

B. T. King,77 D. Kirchmeier,47 J. Kirk,133 A. E. Kiryunin,103 T. Kishimoto,157 D. Kisielewska,41a V. Kitali,45 O. Kivernyk,5

E. Kladiva,146b T. Klapdor-Kleingrothaus,51 M. H. Klein,38 M. Klein,77 U. Klein,77 K. Kleinknecht,86 P. Klimek,110

A. Klimentov,27 R. Klingenberg,46 T. Klingl,23 T. Klioutchnikova,32 E.-E. Kluge,60a P. Kluit,109 S. Kluth,103 E. Kneringer,65

E. B. F. G. Knoops,88 A. Knue,103 A. Kobayashi,157 D. Kobayashi,159 T. Kobayashi,157 M. Kobel,47 M. Kocian,145

P. Kodys,131 T. Koffas,31 E. Koffeman,109 N. M. Köhler,103 T. Koi,145 M. Kolb,60b I. Koletsou,5 A. A. Komar,98,a

Y. Komori,157 T. Kondo,69 N. Kondrashova,36c K. Köneke,51 A. C. König,108 T. Kono,69,ee R. Konoplich,112,ff

N. Konstantinidis,81 R. Kopeliansky,64 S. Koperny,41a A. K. Kopp,51 K. Korcyl,42 K. Kordas,156 A. Korn,81 A. A. Korol,111,d

I. Korolkov,13 E. V. Korolkova,141 O. Kortner,103 S. Kortner,103 T. Kosek,131 V. V. Kostyukhin,23 A. Kotwal,48

A. Koulouris,10 A. Kourkoumeli-Charalampidi,123a,123b C. Kourkoumelis,9 E. Kourlitis,141 V. Kouskoura,27

A. B. Kowalewska,42 R. Kowalewski,172 T. Z. Kowalski,41a C. Kozakai,157 W. Kozanecki,138 A. S. Kozhin,132

V. A. Kramarenko,101 G. Kramberger,78 D. Krasnopevtsev,100 M.W. Krasny,83 A. Krasznahorkay,32 D. Krauss,103

J. A. Kremer,41a J. Kretzschmar,77 K. Kreutzfeldt,55 P. Krieger,161 K. Krizka,33 K. Kroeninger,46 H. Kroha,103 J. Kroll,129

J. Kroll,124 J. Kroseberg,23 J. Krstic,14 U. Kruchonak,68 H. Krüger,23 N. Krumnack,67 M. C. Kruse,48 T. Kubota,91

H. Kucuk,81 S. Kuday,4b J. T. Kuechler,178 S. Kuehn,32 A. Kugel,60a F. Kuger,177 T. Kuhl,45 V. Kukhtin,68 R. Kukla,88

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Y. Kulchitsky,95 S. Kuleshov,34b Y. P. Kulinich,169 M. Kuna,134a,134b T. Kunigo,71 A. Kupco,129 T. Kupfer,46 O. Kuprash,155

H. Kurashige,70 L. L. Kurchaninov,163a Y. A. Kurochkin,95 M. G. Kurth,35a V. Kus,129 E. S. Kuwertz,172 M. Kuze,159

J. Kvita,117 T. Kwan,172 D. Kyriazopoulos,141 A. La Rosa,103 J. L. La Rosa Navarro,26d L. La Rotonda,40a,40b

F. La Ruffa,40a,40b C. Lacasta,170 F. Lacava,134a,134b J. Lacey,45 H. Lacker,17 D. Lacour,83 E. Ladygin,68 R. Lafaye,5

B. Laforge,83 T. Lagouri,179 S. Lai,57 S. Lammers,64 W. Lampl,7 E. Lançon,27 U. Landgraf,51 M. P. J. Landon,79

M. C. Lanfermann,52 V. S. Lang,60a J. C. Lange,13 R. J. Langenberg,32 A. J. Lankford,166 F. Lanni,27 K. Lantzsch,23

A. Lanza,123a A. Lapertosa,53a,53b S. Laplace,83 J. F. Laporte,138 T. Lari,94a F. Lasagni Manghi,22a,22b M. Lassnig,32

T. S. Lau,62a P. Laurelli,50 W. Lavrijsen,16 A. T. Law,139 P. Laycock,77 T. Lazovich,59 M. Lazzaroni,94a,94b B. Le,91

O. Le Dortz,83 E. Le Guirriec,88 E. P. Le Quilleuc,138 M. LeBlanc,172 T. LeCompte,6 F. Ledroit-Guillon,58 C. A. Lee,27

G. R. Lee,133,gg S. C. Lee,153 L. Lee,59 B. Lefebvre,90 G. Lefebvre,83 M. Lefebvre,172 F. Legger,102 C. Leggett,16

G. Lehmann Miotto,32 X. Lei,7 W. A. Leight,45 M. A. L. Leite,26d R. Leitner,131 D. Lellouch,175 B. Lemmer,57

K. J. C. Leney,81 T. Lenz,23 B. Lenzi,32 R. Leone,7 S. Leone,126a,126b C. Leonidopoulos,49 G. Lerner,151 C. Leroy,97

A. A. J. Lesage,138 C. G. Lester,30 M. Levchenko,125 J. Levêque,5 D. Levin,92 L. J. Levinson,175 M. Levy,19 D. Lewis,79

B. Li,36a,hh Changqiao Li,36a H. Li,150 L. Li,36c Q. Li,35a Q. Li,36a S. Li,48 X. Li,36c Y. Li,143 Z. Liang,35a B. Liberti,135a

A. Liblong,161 K. Lie,62c J. Liebal,23 W. Liebig,15 A. Limosani,152 S. C. Lin,182 T. H. Lin,86 B. E. Lindquist,150 A. E. Lionti,52

E. Lipeles,124 A. Lipniacka,15 M. Lisovyi,60b T. M. Liss,169,ii A. Lister,171 A. M. Litke,139 B. Liu,67 H. Liu,92 H. Liu,27

J. K. K. Liu,122 J. Liu,36b J. B. Liu,36a K. Liu,88 L. Liu,169 M. Liu,36a Y. L. Liu,36a Y. Liu,36a M. Livan,123a,123b A. Lleres,58

J. Llorente Merino,35a S. L. Lloyd,79 C. Y. Lo,62b F. Lo Sterzo,153 E. M. Lobodzinska,45 P. Loch,7 F. K. Loebinger,87

A. Loesle,51 K. M. Loew,25 A. Loginov,179,a T. Lohse,17 K. Lohwasser,141 M. Lokajicek,129 B. A. Long,24 J. D. Long,169

R. E. Long,75 L. Longo,76a,76b K. A. Looper,113 J. A. Lopez,34b D. Lopez Mateos,59 I. Lopez Paz,13 A. Lopez Solis,83

J. Lorenz,102 N. Lorenzo Martinez,5 M. Losada,21 P. J. Lösel,102 X. Lou,35a A. Lounis,119 J. Love,6 P. A. Love,75 H. Lu,62a

N. Lu,92 Y. J. Lu,63 H. J. Lubatti,140 C. Luci,134a,134b A. Lucotte,58 C. Luedtke,51 F. Luehring,64 W. Lukas,65 L. Luminari,134a

O. Lundberg,148a,148b B. Lund-Jensen,149 M. S. Lutz,89 P. M. Luzi,83 D. Lynn,27 R. Lysak,129 E. Lytken,84 F. Lyu,35a

V. Lyubushkin,68 H. Ma,27 L. L. Ma,36b Y. Ma,36b G. Maccarrone,50 A. Macchiolo,103 C. M. Macdonald,141 B. Maček,78

J. Machado Miguens,124,128b D. Madaffari,170 R. Madar,37 W. F. Mader,47 A. Madsen,45 J. Maeda,70 S. Maeland,15

T. Maeno,27 A. S. Maevskiy,101 V. Magerl,51 J. Mahlstedt,109 C. Maiani,119 C. Maidantchik,26a A. A. Maier,103 T. Maier,102

A. Maio,128a,128b,128d O. Majersky,146a S. Majewski,118 Y. Makida,69 N. Makovec,119 B. Malaescu,83 Pa. Malecki,42

V. P. Maleev,125 F. Malek,58 U. Mallik,66 D. Malon,6 C. Malone,30 S. Maltezos,10 S. Malyukov,32 J. Mamuzic,170

G. Mancini,50 I. Mandić,78 J. Maneira,128a,128b L. Manhaes de Andrade Filho,26b J. Manjarres Ramos,47 K. H. Mankinen,84

A. Mann,102 A. Manousos,32 B. Mansoulie,138 J. D. Mansour,35a R. Mantifel,90 M. Mantoani,57 S. Manzoni,94a,94b

L. Mapelli,32 G. Marceca,29 L. March,52 L. Marchese,122 G. Marchiori,83 M. Marcisovsky,129 M. Marjanovic,37

D. E. Marley,92 F. Marroquim,26a S. P. Marsden,87 Z. Marshall,16 M. U. F Martensson,168 S. Marti-Garcia,170 C. B. Martin,113

T. A. Martin,173 V. J. Martin,49 B. Martin dit Latour,15 M. Martinez,13,w V. I. Martinez Outschoorn,169 S. Martin-Haugh,133

V. S. Martoiu,28b A. C. Martyniuk,81 A. Marzin,32 L. Masetti,86 T. Mashimo,157 R. Mashinistov,98 J. Masik,87

A. L. Maslennikov,111,d L. Massa,135a,135b P. Mastrandrea,5 A. Mastroberardino,40a,40b T. Masubuchi,157 P. Mättig,178

J. Maurer,28b S. J. Maxfield,77 D. A. Maximov,111,d R. Mazini,153 I. Maznas,156 S. M. Mazza,94a,94b N. C. Mc Fadden,107

G. Mc Goldrick,161 S. P. Mc Kee,92 A. McCarn,92 R. L. McCarthy,150 T. G. McCarthy,103 L. I. McClymont,81

E. F. McDonald,91 J. A. Mcfayden,32 G. Mchedlidze,57 S. J. McMahon,133 P. C. McNamara,91 R. A. McPherson,172,p

S. Meehan,140 T. J. Megy,51 S. Mehlhase,102 A. Mehta,77 T. Meideck,58 K. Meier,60a B. Meirose,44 D. Melini,170,jj

B. R. Mellado Garcia,147c J. D. Mellenthin,57 M. Melo,146a F. Meloni,18 A. Melzer,23 S. B. Menary,87 L. Meng,77

X. T. Meng,92 A. Mengarelli,22a,22b S. Menke,103 E. Meoni,40a,40b S. Mergelmeyer,17 C. Merlassino,18 P. Mermod,52

L. Merola,106a,106b C. Meroni,94a F. S. Merritt,33 A. Messina,134a,134b J. Metcalfe,6 A. S. Mete,166 C. Meyer,124 J-P. Meyer,138

J. Meyer,109 H. Meyer Zu Theenhausen,60a F. Miano,151 R. P. Middleton,133 S. Miglioranzi,53a,53b L. Mijović,49

G. Mikenberg,175 M. Mikestikova,129 M. Mikuž,78 M. Milesi,91 A. Milic,161 D. A. Millar,79 D.W. Miller,33 C. Mills,49

A. Milov,175 D. A. Milstead,148a,148b A. A. Minaenko,132 Y. Minami,157 I. A. Minashvili,68 A. I. Mincer,112 B. Mindur,41a

M. Mineev,68 Y. Minegishi,157 Y. Ming,176 L. M. Mir,13 K. P. Mistry,124 T. Mitani,174 J. Mitrevski,102 V. A. Mitsou,170

A. Miucci,18 P. S. Miyagawa,141 A. Mizukami,69 J. U. Mjörnmark,84 T. Mkrtchyan,180 M. Mlynarikova,131 T. Moa,148a,148b

K. Mochizuki,97 P. Mogg,51 S. Mohapatra,38 S. Molander,148a,148b R. Moles-Valls,23 M. C. Mondragon,93 K. Mönig,45

J. Monk,39 E. Monnier,88 A. Montalbano,150 J. Montejo Berlingen,32 F. Monticelli,74 S. Monzani,94a,94b R.W. Moore,3

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N. Morange,119 D. Moreno,21 M. Moreno Llácer,32 P. Morettini,53a S. Morgenstern,32 D. Mori,144 T. Mori,157 M. Morii,59

M. Morinaga,174 V. Morisbak,121 A. K. Morley,32 G. Mornacchi,32 J. D. Morris,79 L. Morvaj,150 P. Moschovakos,10

M. Mosidze,54b H. J. Moss,141 J. Moss,145,kk K. Motohashi,159 R. Mount,145 E. Mountricha,27 E. J. W. Moyse,89 S. Muanza,88

F. Mueller,103 J. Mueller,127 R. S. P. Mueller,102 D. Muenstermann,75 P. Mullen,56 G. A. Mullier,18 F. J. Munoz Sanchez,87

W. J. Murray,173,133 H. Musheghyan,32 M. Muškinja,78 A. G. Myagkov,132,ll M. Myska,130 B. P. Nachman,16

O. Nackenhorst,52 K. Nagai,122 R. Nagai,69,ee K. Nagano,69 Y. Nagasaka,61 K. Nagata,164 M. Nagel,51 E. Nagy,88

A. M. Nairz,32 Y. Nakahama,105 K. Nakamura,69 T. Nakamura,157 I. Nakano,114 R. F. Naranjo Garcia,45 R. Narayan,11

D. I. Narrias Villar,60a I. Naryshkin,125 T. Naumann,45 G. Navarro,21 R. Nayyar,7 H. A. Neal,92 P. Yu. Nechaeva,98

T. J. Neep,138 A. Negri,123a,123b M. Negrini,22a S. Nektarijevic,108 C. Nellist,119 A. Nelson,166 M. E. Nelson,122

S. Nemecek,129 P. Nemethy,112 M. Nessi,32,mm M. S. Neubauer,169 M. Neumann,178 P. R. Newman,19 T. Y. Ng,62c

T. Nguyen Manh,97 R. B. Nickerson,122 R. Nicolaidou,138 J. Nielsen,139 V. Nikolaenko,132,ll I. Nikolic-Audit,83

K. Nikolopoulos,19 J. K. Nilsen,121 P. Nilsson,27 Y. Ninomiya,157 A. Nisati,134a N. Nishu,35c R. Nisius,103 I. Nitsche,46

T. Nitta,174 T. Nobe,157 Y. Noguchi,71 M. Nomachi,120 I. Nomidis,31 M. A. Nomura,27 T. Nooney,79 M. Nordberg,32

N. Norjoharuddeen,122 O. Novgorodova,47 S. Nowak,103 M. Nozaki,69 L. Nozka,117 K. Ntekas,166 E. Nurse,81 F. Nuti,91

K. O’connor,25 D. C. O’Neil,144 A. A. O’Rourke,45 V. O’Shea,56 F. G. Oakham,31,e H. Oberlack,103 T. Obermann,23

J. Ocariz,83 A. Ochi,70 I. Ochoa,38 J. P. Ochoa-Ricoux,34a S. Oda,73 S. Odaka,69 A. Oh,87 S. H. Oh,48 C. C. Ohm,16

H. Ohman,168 H. Oide,53a,53b H. Okawa,164 Y. Okumura,157 T. Okuyama,69 A. Olariu,28b L. F. Oleiro Seabra,128a

S. A. Olivares Pino,34a D. Oliveira Damazio,27 A. Olszewski,42 J. Olszowska,42 A. Onofre,128a,128e K. Onogi,105

P. U. E. Onyisi,11,aa H. Oppen,121 M. J. Oreglia,33 Y. Oren,155 D. Orestano,136a,136b N. Orlando,62b R. S. Orr,161

B. Osculati,53a,53b,a R. Ospanov,36a G. Otero y Garzon,29 H. Otono,73 M. Ouchrif,137d F. Ould-Saada,121 A. Ouraou,138

K. P. Oussoren,109 Q. Ouyang,35a M. Owen,56 R. E. Owen,19 V. E. Ozcan,20a N. Ozturk,8 K. Pachal,144 A. Pacheco Pages,13

L. Pacheco Rodriguez,138 C. Padilla Aranda,13 S. Pagan Griso,16 M. Paganini,179 F. Paige,27 G. Palacino,64 S. Palazzo,40a,40b

S. Palestini,32 M. Palka,41b D. Pallin,37 E. St. Panagiotopoulou,10 I. Panagoulias,10 C. E. Pandini,126a,126b

J. G. Panduro Vazquez,80 P. Pani,32 S. Panitkin,27 D. Pantea,28b L. Paolozzi,52 Th. D. Papadopoulou,10 K. Papageorgiou,9,t

A. Paramonov,6 D. Paredes Hernandez,179 A. J. Parker,75 M. A. Parker,30 K. A. Parker,45 F. Parodi,53a,53b J. A. Parsons,38

U. Parzefall,51 V. R. Pascuzzi,161 J. M. Pasner,139 E. Pasqualucci,134a S. Passaggio,53a Fr. Pastore,80 S. Pataraia,86 J. R. Pater,87

T. Pauly,32 B. Pearson,103 S. Pedraza Lopez,170 R. Pedro,128a,128b S. V. Peleganchuk,111,d O. Penc,129 C. Peng,35a H. Peng,36a

J. Penwell,64 B. S. Peralva,26b M.M. Perego,138 D. V. Perepelitsa,27 F. Peri,17 L. Perini,94a,94b H. Pernegger,32

S. Perrella,106a,106b R. Peschke,45 V. D. Peshekhonov,68,a K. Peters,45 R. F. Y. Peters,87 B. A. Petersen,32 T. C. Petersen,39

E. Petit,58 A. Petridis,1 C. Petridou,156 P. Petroff,119 E. Petrolo,134a M. Petrov,122 F. Petrucci,136a,136b N. E. Pettersson,89

A. Peyaud,138 R. Pezoa,34b F. H. Phillips,93 P. W. Phillips,133 G. Piacquadio,150 E. Pianori,173 A. Picazio,89 E. Piccaro,79

M. A. Pickering,122 R. Piegaia,29 J. E. Pilcher,33 A. D. Pilkington,87 A.W. J. Pin,87 M. Pinamonti,135a,135b J. L. Pinfold,3

H. Pirumov,45 M. Pitt,175 L. Plazak,146a M.-A. Pleier,27 V. Pleskot,86 E. Plotnikova,68 D. Pluth,67 P. Podberezko,111

R. Poettgen,84 R. Poggi,123a,123b L. Poggioli,119 I. Pogrebnyak,93 D. Pohl,23 G. Polesello,123a A. Poley,45 A. Policicchio,40a,40b

R. Polifka,32 A. Polini,22a C. S. Pollard,56 V. Polychronakos,27 K. Pommes,32 D. Ponomarenko,100 L. Pontecorvo,134a

G. A. Popeneciu,28d S. Pospisil,130 K. Potamianos,16 I. N. Potrap,68 C. J. Potter,30 T. Poulsen,84 J. Poveda,32

M. E. Pozo Astigarraga,32 P. Pralavorio,88 A. Pranko,16 S. Prell,67 D. Price,87 M. Primavera,76a S. Prince,90 N. Proklova,100

K. Prokofiev,62c F. Prokoshin,34b S. Protopopescu,27 J. Proudfoot,6 M. Przybycien,41a A. Puri,169 P. Puzo,119 J. Qian,92

G. Qin,56 Y. Qin,87 A. Quadt,57 M. Queitsch-Maitland,45 D. Quilty,56 S. Raddum,121 V. Radeka,27 V. Radescu,122

S. K. Radhakrishnan,150 P. Radloff,118 P. Rados,91 F. Ragusa,94a,94b G. Rahal,181 J. A. Raine,87 S. Rajagopalan,27

C. Rangel-Smith,168 T. Rashid,119 S. Raspopov,5 M. G. Ratti,94a,94b D. M. Rauch,45 F. Rauscher,102 S. Rave,86

I. Ravinovich,175 J. H. Rawling,87 M. Raymond,32 A. L. Read,121 N. P. Readioff,58 M. Reale,76a,76b D. M. Rebuzzi,123a,123b

A. Redelbach,177 G. Redlinger,27 R. Reece,139 R. G. Reed,147c K. Reeves,44 L. Rehnisch,17 J. Reichert,124 A. Reiss,86

C. Rembser,32 H. Ren,35a M. Rescigno,134a S. Resconi,94a E. D. Resseguie,124 S. Rettie,171 E. Reynolds,19

O. L. Rezanova,111,d P. Reznicek,131 R. Rezvani,97 R. Richter,103 S. Richter,81 E. Richter-Was,41b O. Ricken,23 M. Ridel,83

P. Rieck,103 C. J. Riegel,178 J. Rieger,57 O. Rifki,115 M. Rijssenbeek,150 A. Rimoldi,123a,123b M. Rimoldi,18 L. Rinaldi,22a

G. Ripellino,149 B. Ristić,32 E. Ritsch,32 I. Riu,13 F. Rizatdinova,116 E. Rizvi,79 C. Rizzi,13 R. T. Roberts,87

S. H. Robertson,90,p A. Robichaud-Veronneau,90 D. Robinson,30 J. E. M. Robinson,45 A. Robson,56 E. Rocco,86

C. Roda,126a,126b Y. Rodina,88,nn S. Rodriguez Bosca,170 A. Rodriguez Perez,13 D. Rodriguez Rodriguez,170 S. Roe,32

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C. S. Rogan,59 O. Røhne,121 J. Roloff,59 A. Romaniouk,100 M. Romano,22a,22b S. M. Romano Saez,37 E. Romero Adam,170

N. Rompotis,77 M. Ronzani,51 L. Roos,83 S. Rosati,134a K. Rosbach,51 P. Rose,139 N.-A. Rosien,57 E. Rossi,106a,106b

L. P. Rossi,53a J. H. N. Rosten,30 R. Rosten,140 M. Rotaru,28b J. Rothberg,140 D. Rousseau,119 A. Rozanov,88 Y. Rozen,154

X. Ruan,147c F. Rubbo,145 F. Rühr,51 A. Ruiz-Martinez,31 Z. Rurikova,51 N. A. Rusakovich,68 H. L. Russell,90

J. P. Rutherfoord,7 N. Ruthmann,32 Y. F. Ryabov,125 M. Rybar,169 G. Rybkin,119 S. Ryu,6 A. Ryzhov,132 G. F. Rzehorz,57

A. F. Saavedra,152 G. Sabato,109 S. Sacerdoti,29 H. F-W. Sadrozinski,139 R. Sadykov,68 F. Safai Tehrani,134a P. Saha,110

M. Sahinsoy,60a M. Saimpert,45 M. Saito,157 T. Saito,157 H. Sakamoto,157 Y. Sakurai,174 G. Salamanna,136a,136b

J. E. Salazar Loyola,34b D. Salek,109 P. H. Sales De Bruin,168 D. Salihagic,103 A. Salnikov,145 J. Salt,170 D. Salvatore,40a,40b

F. Salvatore,151 A. Salvucci,62a,62b,62c A. Salzburger,32 D. Sammel,51 D. Sampsonidis,156 D. Sampsonidou,156 J. Sánchez,170

V. Sanchez Martinez,170 A. Sanchez Pineda,167a,167c H. Sandaker,121 R. L. Sandbach,79 C. O. Sander,45 M. Sandhoff,178

C. Sandoval,21 D. P. C. Sankey,133 M. Sannino,53a,53b Y. Sano,105 A. Sansoni,50 C. Santoni,37 H. Santos,128a

I. Santoyo Castillo,151 A. Sapronov,68 J. G. Saraiva,128a,128d B. Sarrazin,23 O. Sasaki,69 K. Sato,164 E. Sauvan,5 G. Savage,80

P. Savard,161,e N. Savic,103 C. Sawyer,133 L. Sawyer,82,v J. Saxon,33 C. Sbarra,22a A. Sbrizzi,22a,22b T. Scanlon,81

D. A. Scannicchio,166 J. Schaarschmidt,140 P. Schacht,103 B. M. Schachtner,102 D. Schaefer,32 L. Schaefer,124 R. Schaefer,45

J. Schaeffer,86 S. Schaepe,23 S. Schaetzel,60b U. Schäfer,86 A. C. Schaffer,119 D. Schaile,102 R. D. Schamberger,150

V. A. Schegelsky,125 D. Scheirich,131 M. Schernau,166 C. Schiavi,53a,53b S. Schier,139 L. K. Schildgen,23 C. Schillo,51

M. Schioppa,40a,40b S. Schlenker,32 K. R. Schmidt-Sommerfeld,103 K. Schmieden,32 C. Schmitt,86 S. Schmitt,45 S. Schmitz,86

U. Schnoor,51 L. Schoeffel,138 A. Schoening,60b B. D. Schoenrock,93 E. Schopf,23 M. Schott,86 J. F. P. Schouwenberg,108

J. Schovancova,32 S. Schramm,52 N. Schuh,86 A. Schulte,86 M. J. Schultens,23 H.-C. Schultz-Coulon,60a H. Schulz,17

M. Schumacher,51 B. A. Schumm,139 Ph. Schune,138 A. Schwartzman,145 T. A. Schwarz,92 H. Schweiger,87

Ph. Schwemling,138 R. Schwienhorst,93 J. Schwindling,138 A. Sciandra,23 G. Sciolla,25 M. Scornajenghi,40a,40b

F. Scuri,126a,126b F. Scutti,91 J. Searcy,92 P. Seema,23 S. C. Seidel,107 A. Seiden,139 J. M. Seixas,26a G. Sekhniaidze,106a

K. Sekhon,92 S. J. Sekula,43 N. Semprini-Cesari,22a,22b S. Senkin,37 C. Serfon,121 L. Serin,119 L. Serkin,167a,167b

M. Sessa,136a,136b R. Seuster,172 H. Severini,115 T. Sfiligoj,78 F. Sforza,165 A. Sfyrla,52 E. Shabalina,57 N.W. Shaikh,148a,148b

L. Y. Shan,35a R. Shang,169 J. T. Shank,24 M. Shapiro,16 P. B. Shatalov,99 K. Shaw,167a,167b S. M. Shaw,87

A. Shcherbakova,148a,148b C. Y. Shehu,151 Y. Shen,115 N. Sherafati,31 P. Sherwood,81 L. Shi,153,oo S. Shimizu,70

C. O. Shimmin,179 M. Shimojima,104 I. P. J. Shipsey,122 S. Shirabe,73 M. Shiyakova,68,pp J. Shlomi,175 A. Shmeleva,98

D. Shoaleh Saadi,97 M. J. Shochet,33 S. Shojaii,94a D. R. Shope,115 S. Shrestha,113 E. Shulga,100 M. A. Shupe,7 P. Sicho,129

A. M. Sickles,169 P. E. Sidebo,149 E. Sideras Haddad,147c O. Sidiropoulou,177 A. Sidoti,22a,22b F. Siegert,47 Dj. Sijacki,14

J. Silva,128a,128d S. B. Silverstein,148a V. Simak,130 Lj. Simic,14 S. Simion,119 E. Simioni,86 B. Simmons,81 M. Simon,86

P. Sinervo,161 N. B. Sinev,118 M. Sioli,22a,22b G. Siragusa,177 I. Siral,92 S. Yu. Sivoklokov,101 J. Sjölin,148a,148b M. B. Skinner,75

P. Skubic,115 M. Slater,19 T. Slavicek,130 M. Slawinska,42 K. Sliwa,165 R. Slovak,131 V. Smakhtin,175 B. H. Smart,5

J. Smiesko,146a N. Smirnov,100 S. Yu. Smirnov,100 Y. Smirnov,100 L. N. Smirnova,101,qq O. Smirnova,84 J. W. Smith,57

M. N. K. Smith,38 R.W. Smith,38 M. Smizanska,75 K. Smolek,130 A. A. Snesarev,98 I. M. Snyder,118 S. Snyder,27

R. Sobie,172,p F. Socher,47 A. Soffer,155 A. Søgaard,49 D. A. Soh,153 G. Sokhrannyi,78 C. A. Solans Sanchez,32 M. Solar,130

E. Yu. Soldatov,100 U. Soldevila,170 A. A. Solodkov,132 A. Soloshenko,68 O. V. Solovyanov,132 V. Solovyev,125 P. Sommer,51

H. Son,165 A. Sopczak,130 D. Sosa,60b C. L. Sotiropoulou,126a,126b R. Soualah,167a,167c A. M. Soukharev,111,d D. South,45

B. C. Sowden,80 S. Spagnolo,76a,76b M. Spalla,126a,126b M. Spangenberg,173 F. Spanò,80 D. Sperlich,17 F. Spettel,103

T. M. Spieker,60a R. Spighi,22a G. Spigo,32 L. A. Spiller,91 M. Spousta,131 R. D. St. Denis,56,a A. Stabile,94a R. Stamen,60a

S. Stamm,17 E. Stanecka,42 R.W. Stanek,6 C. Stanescu,136a M.M. Stanitzki,45 B. S. Stapf,109 S. Stapnes,121

E. A. Starchenko,132 G. H. Stark,33 J. Stark,58 S. H Stark,39 P. Staroba,129 P. Starovoitov,60a S. Stärz,32 R. Staszewski,42

P. Steinberg,27 B. Stelzer,144 H. J. Stelzer,32 O. Stelzer-Chilton,163a H. Stenzel,55 G. A. Stewart,56 M. C. Stockton,118

M. Stoebe,90 G. Stoicea,28b P. Stolte,57 S. Stonjek,103 A. R. Stradling,8 A. Straessner,47 M. E. Stramaglia,18 J. Strandberg,149

S. Strandberg,148a,148b M. Strauss,115 P. Strizenec,146b R. Ströhmer,177 D. M. Strom,118 R. Stroynowski,43 A. Strubig,49

S. A. Stucci,27 B. Stugu,15 N. A. Styles,45 D. Su,145 J. Su,127 S. Suchek,60a Y. Sugaya,120 M. Suk,130 V. V. Sulin,98

DMS Sultan,162a,162b S. Sultansoy,4c T. Sumida,71 S. Sun,59 X. Sun,3 K. Suruliz,151 C. J. E. Suster,152 M. R. Sutton,151

S. Suzuki,69 M. Svatos,129 M. Swiatlowski,33 S. P. Swift,2 I. Sykora,146a T. Sykora,131 D. Ta,51 K. Tackmann,45 J. Taenzer,155

A. Taffard,166 R. Tafirout,163a E. Tahirovic,79 N. Taiblum,155 H. Takai,27 R. Takashima,72 E. H. Takasugi,103 T. Takeshita,142

Y. Takubo,69 M. Talby,88 A. A. Talyshev,111,d J. Tanaka,157 M. Tanaka,159 R. Tanaka,119 S. Tanaka,69 R. Tanioka,70

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B. B. Tannenwald,113 S. Tapia Araya,34b S. Tapprogge,86 S. Tarem,154 G. F. Tartarelli,94a P. Tas,131 M. Tasevsky,129

T. Tashiro,71 E. Tassi,40a,40b A. Tavares Delgado,128a,128b Y. Tayalati,137e A. C. Taylor,107 A. J. Taylor,49 G. N. Taylor,91

P. T. E. Taylor,91 W. Taylor,163b P. Teixeira-Dias,80 D. Temple,144 H. Ten Kate,32 P. K. Teng,153 J. J. Teoh,120 F. Tepel,178

S. Terada,69 K. Terashi,157 J. Terron,85 S. Terzo,13 M. Testa,50 R. J. Teuscher,161,p T. Theveneaux-Pelzer,88 F. Thiele,39

J. P. Thomas,19 J. Thomas-Wilsker,80 P. D. Thompson,19 A. S. Thompson,56 L. A. Thomsen,179 E. Thomson,124

M. J. Tibbetts,16 R. E. Ticse Torres,88 V. O. Tikhomirov,98,rr Yu. A. Tikhonov,111,d S. Timoshenko,100 P. Tipton,179

S. Tisserant,88 K. Todome,159 S. Todorova-Nova,5 S. Todt,47 J. Tojo,73 S. Tokár,146a K. Tokushuku,69 E. Tolley,59

L. Tomlinson,87 M. Tomoto,105 L. Tompkins,145,ss K. Toms,107 B. Tong,59 P. Tornambe,51 E. Torrence,118 H. Torres,47

E. Torró Pastor,140 J. Toth,88,tt F. Touchard,88 D. R. Tovey,141 C. J. Treado,112 T. Trefzger,177 F. Tresoldi,151 A. Tricoli,27

I. M. Trigger,163a S. Trincaz-Duvoid,83 M. F. Tripiana,13 W. Trischuk,161 B. Trocme,58 A. Trofymov,45 C. Troncon,94a

M. Trottier-McDonald,16 M. Trovatelli,172 L. Truong,147b M. Trzebinski,42 A. Trzupek,42 K.W. Tsang,62a J. C-L. Tseng,122

P. V. Tsiareshka,95 G. Tsipolitis,10 N. Tsirintanis,9 S. Tsiskaridze,13 V. Tsiskaridze,51 E. G. Tskhadadze,54a K. M. Tsui,62a

I. I. Tsukerman,99 V. Tsulaia,16 S. Tsuno,69 D. Tsybychev,150 Y. Tu,62b A. Tudorache,28b V. Tudorache,28b T. T. Tulbure,28a

A. N. Tuna,59 S. A. Tupputi,22a,22b S. Turchikhin,68 D. Turgeman,175 I. Turk Cakir,4b,uu R. Turra,94a P. M. Tuts,38

G. Ucchielli,22a,22b I. Ueda,69 M. Ughetto,148a,148b F. Ukegawa,164 G. Unal,32 A. Undrus,27 G. Unel,166 F. C. Ungaro,91

Y. Unno,69 C. Unverdorben,102 J. Urban,146b P. Urquijo,91 P. Urrejola,86 G. Usai,8 J. Usui,69 L. Vacavant,88 V. Vacek,130

B. Vachon,90 K. O. H. Vadla,121 A. Vaidya,81 C. Valderanis,102 E. Valdes Santurio,148a,148b M. Valente,52 S. Valentinetti,22a,22b

A. Valero,170 L. Valery,13 S. Valkar,131 A. Vallier,5 J. A. Valls Ferrer,170 W. Van Den Wollenberg,109 H. van der Graaf,109

P. van Gemmeren,6 J. Van Nieuwkoop,144 I. van Vulpen,109 M. C. van Woerden,109 M. Vanadia,135a,135b W. Vandelli,32

A. Vaniachine,160 P. Vankov,109 G. Vardanyan,180 R. Vari,134a E. W. Varnes,7 C. Varni,53a,53b T. Varol,43 D. Varouchas,119

A. Vartapetian,8 K. E. Varvell,152 J. G. Vasquez,179 G. A. Vasquez,34b F. Vazeille,37 T. Vazquez Schroeder,90 J. Veatch,57

V. Veeraraghavan,7 L. M. Veloce,161 F. Veloso,128a,128c S. Veneziano,134a A. Ventura,76a,76b M. Venturi,172 N. Venturi,32

A. Venturini,25 V. Vercesi,123a M. Verducci,136a,136b W. Verkerke,109 A. T. Vermeulen,109 J. C. Vermeulen,109

M. C. Vetterli,144,e N. Viaux Maira,34b O. Viazlo,84 I. Vichou,169,a T. Vickey,141 O. E. Vickey Boeriu,141

G. H. A. Viehhauser,122 S. Viel,16 L. Vigani,122 M. Villa,22a,22b M. Villaplana Perez,94a,94b E. Vilucchi,50 M. G. Vincter,31

V. B. Vinogradov,68 A. Vishwakarma,45 C. Vittori,22a,22b I. Vivarelli,151 S. Vlachos,10 M. Vogel,178 P. Vokac,130

G. Volpi,126a,126b H. von der Schmitt,103 E. von Toerne,23 V. Vorobel,131 K. Vorobev,100 M. Vos,170 R. Voss,32

J. H. Vossebeld,77 N. Vranjes,14 M. Vranjes Milosavljevic,14 V. Vrba,130 M. Vreeswijk,109 R. Vuillermet,32 I. Vukotic,33

P. Wagner,23 W.Wagner,178 J. Wagner-Kuhr,102 H. Wahlberg,74 S. Wahrmund,47 J. Walder,75 R. Walker,102 W. Walkowiak,143

V. Wallangen,148a,148b C. Wang,35b C. Wang,36b,vv F. Wang,176 H. Wang,16 H. Wang,3 J. Wang,45 J. Wang,152 Q. Wang,115

R. Wang,6 S. M. Wang,153 T. Wang,38 W. Wang,153,ww W. Wang,36a Z. Wang,36c C. Wanotayaroj,118 A. Warburton,90

C. P. Ward,30 D. R. Wardrope,81 A. Washbrook,49 P. M. Watkins,19 A. T. Watson,19 M. F. Watson,19 G. Watts,140 S. Watts,87

B. M. Waugh,81 A. F. Webb,11 S. Webb,86 M. S. Weber,18 S.W. Weber,177 S. A. Weber,31 J. S. Webster,6 A. R. Weidberg,122

B. Weinert,64 J. Weingarten,57 M. Weirich,86 C. Weiser,51 H. Weits,109 P. S. Wells,32 T. Wenaus,27 T. Wengler,32 S. Wenig,32

N. Wermes,23 M. D. Werner,67 P. Werner,32 M. Wessels,60a T. D. Weston,18 K. Whalen,118 N. L. Whallon,140

A. M. Wharton,75 A. S. White,92 A. White,8 M. J. White,1 R. White,34b D. Whiteson,166 B.W. Whitmore,75 F. J. Wickens,133

W. Wiedenmann,176 M. Wielers,133 C. Wiglesworth,39 L. A. M. Wiik-Fuchs,51 A. Wildauer,103 F. Wilk,87 H. G. Wilkens,32

H. H. Williams,124 S. Williams,109 C. Willis,93 S. Willocq,89 J. A. Wilson,19 I. Wingerter-Seez,5 E. Winkels,151

F. Winklmeier,118 O. J. Winston,151 B. T. Winter,23 M. Wittgen,145 M. Wobisch,82,v T. M. H. Wolf,109 R. Wolff,88

M.W. Wolter,42 H. Wolters,128a,128c V. W. S. Wong,171 S. D. Worm,19 B. K. Wosiek,42 J. Wotschack,32 K.W. Wozniak,42

M. Wu,33 S. L. Wu,176 X. Wu,52 Y. Wu,92 T. R. Wyatt,87 B. M. Wynne,49 S. Xella,39 Z. Xi,92 L. Xia,35c D. Xu,35a L. Xu,27

T. Xu,138 B. Yabsley,152 S. Yacoob,147a D. Yamaguchi,159 Y. Yamaguchi,159 A. Yamamoto,69 S. Yamamoto,157

T. Yamanaka,157 F. Yamane,70 M. Yamatani,157 Y. Yamazaki,70 Z. Yan,24 H. Yang,36c H. Yang,16 Y. Yang,153 Z. Yang,15

W-M. Yao,16 Y. C. Yap,83 Y. Yasu,69 E. Yatsenko,5 K. H. Yau Wong,23 J. Ye,43 S. Ye,27 I. Yeletskikh,68 E. Yigitbasi,24

E. Yildirim,86 K. Yorita,174 K. Yoshihara,124 C. Young,145 C. J. S. Young,32 J. Yu,8 J. Yu,67 S. P. Y. Yuen,23 I. Yusuff,30,xx

B. Zabinski,42 G. Zacharis,10 R. Zaidan,13 A. M. Zaitsev,132,ll N. Zakharchuk,45 J. Zalieckas,15 A. Zaman,150 S. Zambito,59

D. Zanzi,91 C. Zeitnitz,178 G. Zemaityte,122 A. Zemla,41a J. C. Zeng,169 Q. Zeng,145 O. Zenin,132 T. Ženiš,146a D. Zerwas,119

D. Zhang,92 F. Zhang,176 G. Zhang,36a,yy H. Zhang,35b J. Zhang,6 L. Zhang,51 L. Zhang,36a M. Zhang,169 P. Zhang,35b

R. Zhang,23 R. Zhang,36a,vv X. Zhang,36b Y. Zhang,35a Z. Zhang,119 X. Zhao,43 Y. Zhao,36b,zz Z. Zhao,36a A. Zhemchugov,68

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B. Zhou,92 C. Zhou,176 L. Zhou,43 M. Zhou,35a M. Zhou,150 N. Zhou,35c C. G. Zhu,36b H. Zhu,35a J. Zhu,92 Y. Zhu,36a

X. Zhuang,35a K. Zhukov,98 A. Zibell,177 D. Zieminska,64 N. I. Zimine,68 C. Zimmermann,86 S. Zimmermann,51

Z. Zinonos,103 M. Zinser,86 M. Ziolkowski,143 L. Živković,14 G. Zobernig,176 A. Zoccoli,22a,22b R. Zou,33

M. zur Nedden,17 and L. Zwalinski32

(ATLAS Collaboration)

1Department of Physics, University of Adelaide, Adelaide, Australia2Physics Department, SUNY Albany, Albany New York, USA

3Department of Physics, University of Alberta, Edmonton Alberta, Canada4aDepartment of Physics, Ankara University, Ankara, Turkey

4bIstanbul Aydin University, Istanbul, Turkey4cDivision of Physics, TOBB University of Economics and Technology, Ankara, Turkey

5LAPP, CNRS/IN2P3 and Universite Savoie Mont Blanc, Annecy-le-Vieux, France6High Energy Physics Division, Argonne National Laboratory, Argonne Illinois, USA

7Department of Physics, University of Arizona, Tucson Arizona, USA8Department of Physics, The University of Texas at Arlington, Arlington Texas, USA

9Physics Department, National and Kapodistrian University of Athens, Athens, Greece10Physics Department, National Technical University of Athens, Zografou, Greece11Department of Physics, The University of Texas at Austin, Austin Texas, USA

12Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan13Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology,

Barcelona, Spain14Institute of Physics, University of Belgrade, Belgrade, Serbia

15Department for Physics and Technology, University of Bergen, Bergen, Norway16Physics Division, Lawrence Berkeley National Laboratory and University of California,

Berkeley California, USA17Department of Physics, Humboldt University, Berlin, Germany

18Albert Einstein Center for Fundamental Physics and Laboratory for High Energy Physics,University of Bern, Bern, Switzerland

19School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom20aDepartment of Physics, Bogazici University, Istanbul, Turkey

20bDepartment of Physics Engineering, Gaziantep University, Gaziantep, Turkey20cIstanbul Bilgi University, Faculty of Engineering and Natural Sciences, Istanbul, Turkey20dBahcesehir University, Faculty of Engineering and Natural Sciences, Istanbul, Turkey

21Centro de Investigaciones, Universidad Antonio Narino, Bogota, Colombia22aINFN Sezione di Bologna, Italy

22bDipartimento di Fisica e Astronomia, Universita di Bologna, Bologna, Italy23Physikalisches Institut, University of Bonn, Bonn, Germany

24Department of Physics, Boston University, Boston Massachusetts, USA25Department of Physics, Brandeis University, Waltham Massachusetts, USA

26aUniversidade Federal do Rio De Janeiro COPPE/EE/IF, Rio de Janeiro, Brazil26bElectrical Circuits Department, Federal University of Juiz de Fora (UFJF), Juiz de Fora, Brazil

26cFederal University of Sao Joao del Rei (UFSJ), Sao Joao del Rei, Brazil26dInstituto de Fisica, Universidade de Sao Paulo, Sao Paulo, Brazil

27Physics Department, Brookhaven National Laboratory, Upton New York, USA28aTransilvania University of Brasov, Brasov, Romania

28bHoria Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania28cDepartment of Physics, Alexandru Ioan Cuza University of Iasi, Iasi, Romania

28dNational Institute for Research and Development of Isotopic and Molecular Technologies,Physics Department, Cluj Napoca, Romania

28eUniversity Politehnica Bucharest, Bucharest, Romania28fWest University in Timisoara, Timisoara, Romania

29Departamento de Física, Universidad de Buenos Aires, Buenos Aires, Argentina30Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom

31Department of Physics, Carleton University, Ottawa Ontario, Canada32CERN, Geneva, Switzerland

33Enrico Fermi Institute, University of Chicago, Chicago Illinois, USA34aDepartamento de Física, Pontificia Universidad Católica de Chile, Santiago, Chile

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34bDepartamento de Física, Universidad Tecnica Federico Santa María, Valparaíso, Chile35aInstitute of High Energy Physics, Chinese Academy of Sciences, Beijing, China

35bDepartment of Physics, Nanjing University, Jiangsu, China35cPhysics Department, Tsinghua University, Beijing 100084, China

36aDepartment of Modern Physics and State Key Laboratory of Particle Detection and Electronics,University of Science and Technology of China, Anhui, China36bSchool of Physics, Shandong University, Shandong, China

36cDepartment of Physics and Astronomy, Key Laboratory for Particle Physics, Astrophysics andCosmology, Ministry of Education; Shanghai Key Laboratory for Particle Physics and Cosmology,

Shanghai Jiao Tong University, Shanghai(also at PKU-CHEP), China37Universite Clermont Auvergne, CNRS/IN2P3, LPC, Clermont-Ferrand, France

38Nevis Laboratory, Columbia University, Irvington New York, USA39Niels Bohr Institute, University of Copenhagen, Kobenhavn, Denmark

40aINFN Gruppo Collegato di Cosenza, Laboratori Nazionali di Frascati, Italy40bDipartimento di Fisica, Universita della Calabria, Rende, Italy

41aAGH University of Science and Technology,Faculty of Physics and Applied Computer Science, Krakow, Poland

41bMarian Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland42Institute of Nuclear Physics Polish Academy of Sciences, Krakow, Poland43Physics Department, Southern Methodist University, Dallas Texas, USA

44Physics Department, University of Texas at Dallas, Richardson Texas, USA45DESY, Hamburg and Zeuthen, Germany

46Lehrstuhl für Experimentelle Physik IV, Technische Universität Dortmund, Dortmund, Germany47Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden, Germany

48Department of Physics, Duke University, Durham North Carolin, USA49SUPA - School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom

50INFN e Laboratori Nazionali di Frascati, Frascati, Italy51Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg, Germany

52Departement de Physique Nucleaire et Corpusculaire, Universite de Geneve, Geneva, Switzerland53aINFN Sezione di Genova, Italy

53bDipartimento di Fisica, Universita di Genova, Genova, Italy54aE. Andronikashvili Institute of Physics, Iv. Javakhishvili Tbilisi State University, Tbilisi, Georgia

54bHigh Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia55II Physikalisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany

56SUPA - School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom57II Physikalisches Institut, Georg-August-Universität, Göttingen, Germany

58Laboratoire de Physique Subatomique et de Cosmologie, Universite Grenoble-Alpes,CNRS/IN2P3, Grenoble, France

59Laboratory for Particle Physics and Cosmology, Harvard University, Cambridge Massachusetts, USA60aKirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany

60bPhysikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany61Faculty of Applied Information Science, Hiroshima Institute of Technology, Hiroshima, Japan

62aDepartment of Physics, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China62bDepartment of Physics, The University of Hong Kong, Hong Kong, China

62cDepartment of Physics and Institute for Advanced Study, The Hong Kong University of Science andTechnology, Clear Water Bay, Kowloon, Hong Kong, China

63Department of Physics, National Tsing Hua University, Taiwan, Taiwan64Department of Physics, Indiana University, Bloomington Indiana, USA

65Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität, Innsbruck, Austria66University of Iowa, Iowa City Iowa, USA

67Department of Physics and Astronomy, Iowa State University, Ames Iowa, USA68Joint Institute for Nuclear Research, JINR Dubna, Dubna, Russia

69KEK, High Energy Accelerator Research Organization, Tsukuba, Japan70Graduate School of Science, Kobe University, Kobe, Japan

71Faculty of Science, Kyoto University, Kyoto, Japan72Kyoto University of Education, Kyoto, Japan

73Research Center for Advanced Particle Physics and Department of Physics, Kyushu University,Fukuoka, Japan

74Instituto de Física La Plata, Universidad Nacional de La Plata and CONICET, La Plata, Argentina75Physics Department, Lancaster University, Lancaster, United Kingdom

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76aINFN Sezione di Lecce, Italy76bDipartimento di Matematica e Fisica, Universita del Salento, Lecce, Italy

77Oliver Lodge Laboratory, University of Liverpool, Liverpool, United Kingdom78Department of Experimental Particle Physics, Jožef Stefan Institute and Department of Physics,

University of Ljubljana, Ljubljana, Slovenia79School of Physics and Astronomy, Queen Mary University of London, London, United Kingdom

80Department of Physics, Royal Holloway University of London, Surrey, United Kingdom81Department of Physics and Astronomy, University College London, London, United Kingdom

82Louisiana Tech University, Ruston Louisiana, USA83Laboratoire de Physique Nucleaire et de Hautes Energies, UPMC and Universite Paris-Diderot and

CNRS/IN2P3, Paris, France84Fysiska institutionen, Lunds universitet, Lund, Sweden

85Departamento de Fisica Teorica C-15, Universidad Autonoma de Madrid, Madrid, Spain86Institut für Physik, Universität Mainz, Mainz, Germany

87School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom88CPPM, Aix-Marseille Universite and CNRS/IN2P3, Marseille, France

89Department of Physics, University of Massachusetts, Amherst Massachusetts, USA90Department of Physics, McGill University, Montreal Quebec, Canada

91School of Physics, University of Melbourne, Victoria, Australia92Department of Physics, The University of Michigan, Ann Arbor Michigan, USA

93Department of Physics and Astronomy, Michigan State University, East Lansing Michigan, USA94aINFN Sezione di Milano, Italy

94bDipartimento di Fisica, Universita di Milano, Milano, Italy95B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk, Republic of Belarus96Research Institute for Nuclear Problems of Byelorussian State University, Minsk, Republic of Belarus

97Group of Particle Physics, University of Montreal, Montreal Quebec, Canada98P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow, Russia

99Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia100National Research Nuclear University MEPhI, Moscow, Russia

101D.V. Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University,Moscow, Russia

102Fakultät für Physik, Ludwig-Maximilians-Universität München, München, Germany103Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), München, Germany

104Nagasaki Institute of Applied Science, Nagasaki, Japan105Graduate School of Science and Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Japan

106aINFN Sezione di Napoli, Italy106bDipartimento di Fisica, Universita di Napoli, Napoli, Italy

107Department of Physics and Astronomy, University of New Mexico, Albuquerque New Mexico, USA108Institute for Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen/Nikhef,

Nijmegen, Netherlands109Nikhef National Institute for Subatomic Physics and University of Amsterdam, Amsterdam, Netherlands

110Department of Physics, Northern Illinois University, DeKalb Illinois, USA111Budker Institute of Nuclear Physics, SB RAS, Novosibirsk, Russia

112Department of Physics, New York University, New York New York, USA113Ohio State University, Columbus Ohio, USA

114Faculty of Science, Okayama University, Okayama, Japan115Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma,

Norman Oklahoma, USA116Department of Physics, Oklahoma State University, Stillwater Oklahoma, USA

117Palacký University, RCPTM, Olomouc, Czech Republic118Center for High Energy Physics, University of Oregon, Eugene Oregon, USA119LAL, Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Orsay, France

120Graduate School of Science, Osaka University, Osaka, Japan121Department of Physics, University of Oslo, Oslo, Norway

122Department of Physics, Oxford University, Oxford, United Kingdom123aINFN Sezione di Pavia, Italy

123bDipartimento di Fisica, Universita di Pavia, Pavia, Italy124Department of Physics, University of Pennsylvania, Philadelphia Pennsylvania, USA

125National Research Centre “Kurchatov Institute” B.P.Konstantinov Petersburg Nuclear PhysicsInstitute, St. Petersburg, Russia

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126aINFN Sezione di Pisa, Italy126bDipartimento di Fisica E. Fermi, Universita di Pisa, Pisa, Italy

127Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh Pennsylvania, USA128aLaboratório de Instrumentação e Física Experimental de Partículas - LIP, Lisboa, Portugal

128bFaculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal128cDepartment of Physics, University of Coimbra, Coimbra, Portugal

128dCentro de Física Nuclear da Universidade de Lisboa, Lisboa, Portugal128eDepartamento de Fisica, Universidade do Minho, Braga, Portugal

128fDepartamento de Fisica Teorica y del Cosmos and CAFPE, Universidad de Granada,Granada, Spain

128gDep Fisica and CEFITEC of Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa,Caparica, Portugal

129Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic130Czech Technical University in Prague, Praha, Czech Republic

131Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic132State Research Center Institute for High Energy Physics (Protvino), NRC KI, Russia

133Particle Physics Department, Rutherford Appleton Laboratory, Didcot, United Kingdom134aINFN Sezione di Roma, Italy

134bDipartimento di Fisica, Sapienza Universita di Roma, Roma, Italy135aINFN Sezione di Roma Tor Vergata, Italy

135bDipartimento di Fisica, Universita di Roma Tor Vergata, Roma, Italy136aINFN Sezione di Roma Tre, Italy

136bDipartimento di Matematica e Fisica, Universita Roma Tre, Roma, Italy137aFaculte des Sciences Ain Chock, Reseau Universitaire de Physique des Hautes Energies - Universite

Hassan II, Casablanca, Morocco137bCentre National de l’Energie des Sciences Techniques Nucleaires, Rabat, Morocco137cFaculte des Sciences Semlalia, Universite Cadi Ayyad, LPHEA-Marrakech, Morocco137dFaculte des Sciences, Universite Mohamed Premier and LPTPM, Oujda, Morocco

137eFaculte des sciences, Universite Mohammed V, Rabat, Morocco138DSM/IRFU (Institut de Recherches sur les Lois Fondamentales de l’Univers), CEA Saclay(Commissariat a l’Energie Atomique et aux Energies Alternatives), Gif-sur-Yvette, France

139Santa Cruz Institute for Particle Physics, University of California Santa Cruz,Santa Cruz California, USA

140Department of Physics, University of Washington, Seattle Washington, USA141Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom

142Department of Physics, Shinshu University, Nagano, Japan143Department Physik, Universität Siegen, Siegen, Germany

144Department of Physics, Simon Fraser University, Burnaby British Columbia, Canada145SLAC National Accelerator Laboratory, Stanford California, USA

146aFaculty of Mathematics, Physics & Informatics, Comenius University, Bratislava, Slovak Republic146bDepartment of Subnuclear Physics, Institute of Experimental Physics of the Slovak Academy of

Sciences, Kosice, Slovak Republic147aDepartment of Physics, University of Cape Town, Cape Town, South Africa

147bDepartment of Physics, University of Johannesburg, Johannesburg, South Africa147cSchool of Physics, University of the Witwatersrand, Johannesburg, South Africa

148aDepartment of Physics, Stockholm University, Sweden148bThe Oskar Klein Centre, Stockholm, Sweden

149Physics Department, Royal Institute of Technology, Stockholm, Sweden150Departments of Physics & Astronomy and Chemistry, Stony Brook University,

Stony Brook New York, USA151Department of Physics and Astronomy, University of Sussex, Brighton, United Kingdom

152School of Physics, University of Sydney, Sydney, Australia153Institute of Physics, Academia Sinica, Taipei, Taiwan

154Department of Physics, Technion: Israel Institute of Technology, Haifa, Israel155Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv, Israel

156Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece157International Center for Elementary Particle Physics and Department of Physics,

The University of Tokyo, Tokyo, Japan158Graduate School of Science and Technology, Tokyo Metropolitan University, Tokyo, Japan

159Department of Physics, Tokyo Institute of Technology, Tokyo, Japan

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160Tomsk State University, Tomsk, Russia161Department of Physics, University of Toronto, Toronto Ontario, Canada

162aINFN-TIFPA, Italy162bUniversity of Trento, Trento, Italy

163aTRIUMF, Vancouver British Columbia, Canada163bDepartment of Physics and Astronomy, York University, Toronto Ontario, Canada

164Faculty of Pure and Applied Sciences, and Center for Integrated Research in Fundamental Science andEngineering, University of Tsukuba, Tsukuba, Japan

165Department of Physics and Astronomy, Tufts University, Medford Massachusetts, USA166Department of Physics and Astronomy, University of California Irvine, Irvine California, USA

167aINFN Gruppo Collegato di Udine, Sezione di Trieste, Udine, Italy167bICTP, Trieste, Italy

167cDipartimento di Chimica, Fisica e Ambiente, Universita di Udine, Udine, Italy168Department of Physics and Astronomy, University of Uppsala, Uppsala, Sweden

169Department of Physics, University of Illinois, Urbana Illinois, USA170Instituto de Fisica Corpuscular (IFIC), Centro Mixto Universidad de Valencia - CSIC, Spain171Department of Physics, University of British Columbia, Vancouver British Columbia, Canada

172Department of Physics and Astronomy, University of Victoria, Victoria British Columbia, Canada173Department of Physics, University of Warwick, Coventry, United Kingdom

174Waseda University, Tokyo, Japan175Department of Particle Physics, The Weizmann Institute of Science, Rehovot, Israel

176Department of Physics, University of Wisconsin, Madison Wisconsin, USA177Fakultät für Physik und Astronomie, Julius-Maximilians-Universität, Würzburg, Germany

178Fakultät für Mathematik und Naturwissenschaften, Fachgruppe Physik,Bergische Universität Wuppertal, Wuppertal, Germany

179Department of Physics, Yale University, New Haven Connecticut, USA180Yerevan Physics Institute, Yerevan, Armenia

181Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules (IN2P3),Villeurbanne, France

182Academia Sinica Grid Computing, Institute of Physics, Academia Sinica, Taipei, Taiwan

aDeceased.bAlso at Department of Physics, King’s College London, London, United Kingdom.cAlso at Institute of Physics, Azerbaijan Academy of Sciences, Baku, Azerbaijan.dAlso at Novosibirsk State University, Novosibirsk, Russia.eAlso at TRIUMF, Vancouver BC, Canada.fAlso at Department of Physics & Astronomy, University of Louisville, Louisville, KY, USA.gAlso at Physics Department, An-Najah National University, Nablus, Palestine.hAlso at Department of Physics, California State University, Fresno CA, USA.iAlso at Department of Physics, University of Fribourg, Fribourg, Switzerland.jAlso at II Physikalisches Institut, Georg-August-Universität, Göttingen, Germany.kAlso at Departament de Fisica de la Universitat Autonoma de Barcelona, Barcelona, Spain.lAlso at Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Portugal.mAlso at Tomsk State University, Tomsk, Russia.nAlso at The Collaborative Innovation Center of Quantum Matter (CICQM), Beijing, China.oAlso at Universita di Napoli Parthenope, Napoli, Italy.pAlso at Institute of Particle Physics (IPP), Canada.qAlso at Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania.rAlso at Department of Physics, St. Petersburg State Polytechnical University, St. Petersburg, Russia.sAlso at Borough of Manhattan Community College, City University of New York, New York City, USA.tAlso at Department of Financial and Management Engineering, University of the Aegean, Chios, Greece.uAlso at Centre for High Performance Computing, CSIR Campus, Rosebank, Cape Town, South Africa.vAlso at Louisiana Tech University, Ruston LA, USA.wAlso at Institucio Catalana de Recerca i Estudis Avancats, ICREA, Barcelona, Spain.xAlso at Graduate School of Science, Osaka University, Osaka, Japan.yAlso at Fakultät für Mathematik und Physik, Albert-Ludwigs-Universität, Freiburg, Germany.zAlso at Institute for Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen/Nikhef, Nijmegen,Netherlands.

aaAlso at Department of Physics, The University of Texas at Austin, Austin TX, USA.bbAlso at Institute of Theoretical Physics, Ilia State University, Tbilisi, Georgia.

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ccAlso at CERN, Geneva, Switzerland.ddAlso at Georgian Technical University (GTU),Tbilisi, Georgia.eeAlso at Ochadai Academic Production, Ochanomizu University, Tokyo, Japan.ffAlso at Manhattan College, New York NY, USA.ggAlso at Departamento de Física, Pontificia Universidad Católica de Chile, Santiago, Chile.hhAlso at Department of Physics, The University of Michigan, Ann Arbor MI, USA.iiAlso at The City College of New York, New York NY, USA.jjAlso at Departamento de Fisica Teorica y del Cosmos and CAFPE, Universidad de Granada, Granada, Spain.kkAlso at Department of Physics, California State University, Sacramento CA, USA.llAlso at Moscow Institute of Physics and Technology State University, Dolgoprudny, Russia.

mmAlso at Departement de Physique Nucleaire et Corpusculaire, Universite de Geneve, Geneva, Switzerland.nnAlso at Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Barcelona, Spain.ooAlso at School of Physics, Sun Yat-sen University, Guangzhou, China.ppAlso at Institute for Nuclear Research and Nuclear Energy (INRNE) of the Bulgarian Academy of Sciences, Sofia, Bulgaria.qqAlso at Faculty of Physics, M.V.Lomonosov Moscow State University, Moscow, Russia.rrAlso at National Research Nuclear University MEPhI, Moscow, Russia.ssAlso at Department of Physics, Stanford University, Stanford CA, USA.ttAlso at Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Budapest, Hungary.uuAlso at Giresun University, Faculty of Engineering, Turkey.vvAlso at CPPM, Aix-Marseille Universite and CNRS/IN2P3, Marseille, France.wwAlso at Department of Physics, Nanjing University, Jiangsu, China.xxAlso at University of Malaya, Department of Physics, Kuala Lumpur, Malaysia.yyAlso at Institute of Physics, Academia Sinica, Taipei, Taiwan.zzAlso at LAL, Univ. Paris-Sud, CNRS/IN2P3, Universite Paris-Saclay, Orsay, France.

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